Alright guys well I went to the Trek store today, and got them to tell me what size and blah blah.

I need a 21 inch bike, and I'm not sure if I want a mountain bike (4300) or more of a hybrid (i liked the su100)

I live in florida so it is very flat, and I'd probably be riding mainly on roads, sidewalks, and the occasional grass and dirt.

Which do you think would be better for me??? Thanks Alot!