Both w and b work with counts, 6w will move you forward 6 words and so on. Moving by sentences and paragraphs and marking your spot You can also move by sentences although I have a personal problem with vi's definition of a sentence. I find this definition of a sentence awkward as few editors require it, and some even consider it old fashioned. One space should be enough, but vi is set in its ways. There are also paragraph movement keys.
Paragraphs are groups of text delimited by blank lines.
These movement keys alone would be quite powerful, but they can additionally be modified with counts. The ex escape mode provides some other useful movement commands. You can move directly to a line in a text file by typing a colon followed by the line number of the line you want to go to. You can also move to a line offset from your current location. It's also possible to move back to a position you've marked.