Add some sort of interesting twist or unique aspect to the features of the first rooms. Some examples include a bottomless pit, giant glowing mushroom, pool of water, spider webs, stalactites precariously hanging from the ceiling, etc. Don’t be afriad to make some very interesting features and also feel free to do more than one per room:

Room #1	
Room Features	

A tile mosaic of legendary monsters covers the floor, and someone has scrawled a diagram of a mechanical trap on the east wall
Monster	

Illusionist (cr 3, motm 263, vgm 214) and 1 x Guard (cr 1/8, mm 347); easy, 725 xp

Treasure: 5 pp; 18 sp
Trap	

Poison Gas Trap: DC 15 to find, DC 10 to disable; affects all targets within a 10 ft. square area, DC 18 save or take 4d10 poison damage
Room #2	
Room Features	

A clicking noise can be faintly heard near the east wall, and a pair of boots lies in the north side of the room
Room #3	
Monster	

Bandit Captain (cr 2, mm 344) and 5 x Bandit (cr 1/8, mm 343); medium, 575 xp

Treasure: 9 ep; 18 sp; 13 gp; 10 gp; 21 cp; 13 gp
Hidden Treasure	

Hidden (DC 25 to find) Trapped and Locked Iron Chest (DC 25 to unlock, DC 30 to break; 60 hp)

Teleporter Crystal: DC 15 to find, DC 15 to disable; affects each creature which touches the crystal, DC 19 save or be teleported to another location

1300 cp, 700 sp, 50 gp, a bone puzzle box engraved with spirals (25 gp), a cloth coat trimmed with rabbit fur (25 gp), a cloth mantle trimmed with fox fur (25 gp), a copper mask inlaid with ornate silver scrollwork (25 gp), a copper ring inlaid with gold (25 gp), a scroll of calligraphy (25 gp), an agateware cup embossed with draconic runes (25 gp), an obsidian orb engraved with arcane runes (25 gp), Spell Scroll (Blade Ward) (common, dmg 200), Spell Scroll (Longstrider) (common, dmg 200), Spell Scroll (Misty Step) (uncommon, dmg 200), 3 x Potion of Healing (common, dmg 187)
Room #4	
Monster	

Orc Eye of Gruumsh (cr 2, mm 247) and 3 x Orc (cr 1/2, mm 246); hard, 750 xp

Treasure: 16 cp; 17 cp; 4 pp; 15 sp
Trap	

Idol of Law: DC 15 to find, DC 15 to disable; affects chaotic creatures which touch the idol, DC 13 save or take 2d10 damage and be stunned for 1 round
Room #5	
Room Features	

Skeletons hang from chains and manacles against the south and east walls, and several pieces of broken glass are scattered throughout the room
Room #6	
Monster	

Ettin (cr 4, mm 132); easy, 1100 xp

Treasure: 18 cp
Room #7	
Monster	

Cult Fanatic (cr 2, mm 345) and 3 x Thug (cr 1/2, mm 350); hard, 750 xp

Treasure: 17 cp; 10 cp; 17 sp; 12 ep
Room #8	
Hidden Treasure	

Locked Simple Wooden Chest (DC 15 to unlock, DC 15 to break; 10 hp)

2800 cp, 900 sp, 40 gp, 4 x diamond (50 gp), chalcedony (50 gp), moonstone (50 gp), onyx (50 gp), sardonyx (50 gp), Medallion of Thoughts (uncommon, dmg 181), +1 Weapon (shortbow) (uncommon, dmg 213)
Room #9	
Hidden Treasure	

Hidden (DC 15 to find) Trapped and Locked Simple Wooden Chest (DC 20 to unlock, DC 15 to break; 10 hp)

Magic Missle Trap: DC 15 to find, DC 10 to disable; one target, 2d10 force damage

2100 cp, 900 sp, 80 gp, a cloth cloak threaded with dyed silk (25 gp), a leather scabbard sewn with copper (25 gp), a malachite cup engraved with arcane runes (25 gp), a necklace of malachite (25 gp), a steel bell engraved with elven script (25 gp), Spell Scroll (Command) (common, dmg 200)
Room #10	
Room Features	

Someone has scrawled "Mind the gap" on the west wall, and a corroded iron key hangs from a hook on the east and west walls
Monster	

Cult Fanatic (cr 2, mm 345) and 3 x Cultist (cr 1/8, mm 345); medium, 525 xp

Treasure: 10 gp; 12 cp; 18 sp; 11 gp
Room #11	
Room Features	

Someone has scrawled "Dinain stands here, slain by a basilisk" on the south wall, and an unexplained breeze can be felt in the east side of the room
Room #12	
Room Features	

A set of demonic war masks hangs on the north wall, and a shattered hammer lies in the center of the room
Monster	

2 x Orog (cr 2, mm 247); hard, 900 xp

Treasure: 8 gp; 21 sp
Room #13	
Room Features	

A stair ascends to a balcony hanging from the west wall, and a mural of ancient mythology covers the ceiling
Monster	

Cult Fanatic (cr 2, mm 345) and 6 x Cultist (cr 1/8, mm 345); deadly, 600 xp

Treasure: 1700 cp, 1700 sp, 30 gp, a bone shield brooch engraved with spirals (25 gp), a cloth cloak trimmed with fur (25 gp), a lacquered wooden cup set with a single alexandrite (25 gp), Spell Scroll (Aura of Life) (rare, dmg 200), Potion of Mind Reading (rare, dmg 188)
Room #14	
Room Features	

Several alcoves are cut into the south and west walls, and someone has scrawled an incomplete drawing of a dragon on the east wall
Monster	

Ettin (cr 4, mm 132); easy, 1100 xp

Treasure: 8 gp
Room #15	
Hidden Treasure	

Hidden (DC 15 to find) Locked Good Wooden Chest (DC 20 to unlock, DC 20 to break; 15 hp)

2600 cp, 800 sp, 90 gp, a fine leather merchant's cap trimmed with lynx fur (25 gp), a pewter mask set with garnet and jet (25 gp), a silver pendant engraved with draconic scales (25 gp), a silver salt cellar set with amethyst (25 gp)
Room #16	
Room Features	

A simple fireplace sits against the north wall, and howling can be faintly heard near the south wall
Monster	

Orc War Chief (cr 4, mm 246) and 1 x Orc (cr 1/2, mm 246); medium, 1200 xp

Treasure: 1 pp; 18 cp
Room #17	
Trap	

Chain Flail: DC 10 to find, DC 10 to disable; initiative +1, 1 attack per round, +7 to hit against all targets within 5 ft., 2d10 bludgeoning damage
Hidden Treasure	

Hidden (DC 20 to find) Trapped and Unlocked Simple Wooden Chest (10 hp)

Acid Spray: DC 20 to find, DC 20 to disable; affects all targets within a 20 ft. cone, DC 19 save or take 2d10 acid damage for 1d4 rounds

2500 cp, 600 sp, 80 gp, 4 x diamond (50 gp), chalcedony (50 gp), jasper (50 gp), sardonyx (50 gp), zircon (50 gp)
Room #18	
Room Features	

A cube of solid stone stands in the west side of the room, and a sulphurous odor fills the room
Room #19	
Room Features	

A narrow pit covered by iron bars lies in the center of the room, and someone has scrawled "I've forgotten my name" on the west wall
Monster	

2 x Goblin (cr 1/4, mm 166) and 2 x Wolf (cr 1/4, mm 341); easy, 200 xp

Treasure: 19 sp; 13 cp; 15 gp; 15 sp
Room #20	
Room Features	

A cube of solid stone stands in the north-west corner of the room, and the walls are covered with slime
Room #21	
Room Features	

Someone has scrawled "The Golden Wayfarers looted this place" in dwarvish runes on the north wall, and a rusted breastplate lies in the south-west corner of the room
Monster	

3 x Bugbear (cr 1, mm 33) and 1 x Half-ogre (cr 1, mm 238); deadly, 800 xp

Treasure: 20 cp; 24 cp; 18 cp; 10 ep
Room #22	
Room Features	

A faded and torn tapestry hangs from the north wall, and skeletons hang from chains and manacles against the east and west walls
Monster	

Orc War Chief (cr 4, mm 246) and 1 x Orc (cr 1/2, mm 246); medium, 1200 xp

Treasure: 12 sp; 11 sp
Room #23	
Room Features	

Part of the east wall has collapsed into the room, and the floor is covered in square tiles, alternating white and black
Monster	

Ogre Battering Ram (cr 4, motm 200, mtf 220) and 1 x Ogre (cr 2, mm 237); deadly, 1550 xp

Treasure: 2100 cp, 1200 sp, 120 gp, a linen merchant's cap trimmed with squirrel fur (25 gp), a marble coffer inlaid with silver (25 gp), a pewter tankard engraved with dwarven axeheads (25 gp), a rosewood rod engraved with floral vines (25 gp), a scroll of calligraphy (25 gp), an agate salt cellar engraved with a labyrinth (25 gp), Boots of Elvenkind (uncommon, dmg 155), Boots of Striding and Springing (uncommon, dmg 156), Gloves of Thievery (uncommon, dmg 172), Ring of Jumping (uncommon, dmg 191)
Room #24	
Room Features	

Ghostly music fills the room, and a charred wooden shield lies in the west side of the room
Room #25	
Room Features	

A group of monstrous faces have been carved into the east wall, and the ceiling is covered with cracks
Monster	

2 x Orc (cr 1/2, mm 246) and 1 x Half-ogre (cr 1, mm 238); medium, 400 xp

Treasure: 11 gp; 5 pp; 13 ep
Trap	

Ice Dart Trap: DC 15 to find, DC 15 to disable; +8 to hit against one target, 2d10 cold damage
Room #26	
Monster	

Ettin (cr 4, mm 132); easy, 1100 xp

Treasure: 18 cp
Room #27	
Room Features	

The floor is covered in square tiles, alternating white and black, and someone has scrawled a drawing of a door on the south wall
Monster	

4 x Orc (cr 1/2, mm 246) and 1 x Half-ogre (cr 1, mm 238); hard, 600 xp

Treasure: 1800 cp, 1200 sp, 40 gp, a bone medallion engraved with draconic scales (25 gp), a cloth coat trimmed with fur (25 gp), a fine leather mantle trimmed with rabbit fur (25 gp), a fine leather merchant's cap trimmed with fox fur (25 gp), a necklace of malachite (25 gp), Spell Scroll (Purify Food and Drink) (common, dmg 200), Driftglobe (uncommon, dmg 166), Potion of Climbing (common, dmg 187), Potion of Healing (common, dmg 187)
Room #28	
Monster	

4 x Goblin (cr 1/4, mm 166); easy, 200 xp

Treasure: 4 pp; 12 cp; 19 cp; 18 cp
Room #29	
Room Features	

The room has a high domed ceiling, and someone has scrawled "Boda died here" on the north wall
Trap	

Electrified Floortile: DC 15 to find, DC 10 to disable; affects all targets within a 10 ft. square area, DC 15 save or take 2d10 lightning damage
Room #30	
Monster	

Wight (cr 3, mm 300) and 2 x Zombie (cr 1/4, mm 316); deadly, 800 xp

Treasure: 9 gp; 12 ep; 8 gp