I have been doing a bit of research on this, since I want to get a comfort bike for commuting around town (errands, quick trips to grocery store for those things you end up buying mid week like milk, etc).
Here is a good forum for you to check out:
Also, someone pointed me to a really cool site:
http://www.sueandpaul.com/gmapPedometer/
Someone used google's maps so that you can plan a walking/bike riding trip...just trace your route and it will give you the mileage...this is handy, I think, because you don't have to have ending address, and usually when you look up directions on maps.google.com or others, it will give the best driving directions, that are not usually the best walking or bike riding directions.
Good luck...I hope you find a good bike. Your local bike shop will usually let you do a layaway plan if you need to. Worst case scenario, if you have to get one at Walmart, if you don't have the knowledge to do it your self, take that bike to be tuned up at a bike shop, because they usually are not put together too well at walmart (or put it together yourself).
I may just go get a cheap walmart one, and put a really nice bike on layaway in a few months because I don't want money to stop me from getting back on a bike.