I worked part time for a couple of summers a couple of years ago at an LBS and when the salespeople got too busy I got to come out of the service area and help folks out. I'd ask a few questions to get a feel for how comfortable they were with shifting in general, if they thought that they might like the brake/shifter style shifting, the grip rotating shifters, the rapid-fire style trigger shifters, bar ends, or no shifters at all, doing this while walking around the sales floor looking at different bikes with the different setups on them to give the customers a hands-on feel for what I was talking about. Then I'd have them sit on a few bikes with me holding the bike up to let them feel first hand the differences between a more compact geometry and a more stretched out geometry. Eventually we'd end up with one to three bikes that they seemed to like, all within their general price range, at which point I'd suggest either a parking lot test ride, or putting the bike up on a trainer so they could get a good feel for how it rides or in the case of the trainer at least feel what it feels like to pedal the bike. This let them decide what would work for them, what they would be most comfortable with, and what they liked the best. And sometimes they'd just pick one based on the color.
http://www.trekbikes.com/us/en/bikes..._series/7500/#
Sit on that 7500, test ride it if you can, and if it feels right and fits your budget then it should be fine. Since it seems to take a 35c tire width it should work fine on most any trail or bike path in your area.