I am Diana. I lived several years in Washington DC as a newlywed poor graduate student and used a bike all the time. Then I came back, got a job, had kids, got fat , had a serious neck injury, developed carpal tunnel and stopped biking. Now my oldest kid is 5 and is a bike enthusiast so I want to get back to biking.
Back in my student years I went back and forth from mountain bike to so-called hybrid bikes and I was never happy with either. As I am very short and started riding late in life I prefer mountain bikes as I find them easier to maneuver, but I always end up being convinced to get something "faster". My last bike in DC was a man's Trek 720 (I think the granddad of the 7200) in a 13in frame and it was OK. It was stolen so I bought the closest thing, a woman's trek 7200, size 14.5 and I don't like it. Maybe it's the years off the bike but it feels huge and not very easy to maneuver in tight corners. I can still exchange it, but I'm not sure for what. I still think the best for me would be a simple mountain bike with no suspension, and probably change the tires. I know they're slower, but I don't think my 5 year old will go very fast in his 16" wheeler any time soon.