Check the coating. You should be able to see the shiny, waterproof coating on the inside of the rainfly and floor. If you can't see and feel it on the fabric, it may not be thick enough to stand up to heavy use. Pick the right color. Check how well the tent's color transmits light to the interior.
Some colors create a bright interior, while others make for a dreary, cavelike ambience.
Light colors are cooler in the summer, while dark colors absorb solar energy, making them better for cold weather.