As others have said, go to a bike shop not the big box stores. You won't regret it, especially if you get "hooked" and start thinking about doing some distance riding (50 - 100 miles or more). Talk to people in your local cycling club.
I would also invite you to join the "dark side", as DF (Diamond Frame) riders refer to us.
Look into a
RECUMBENT bicycle (or trike). At least try one.
You ride in a reclined seat with your legs in front of you.
Pros:
No hand pain! No butt pain! No Neck Pain!
Enjoy the scenery because your head it facing up and forward all of the time.
Fast down hills and flat riding (more aerodynamic)
Many "cool bike Dude" comments
Cons:
Good "bents" are more expensive than comparable DFs
Hill climbing is a bit slower (spin vs. stand)
It takes a bit to get used to the difference is balance points
You will need a little time to develop your "bent" muscles
I don't think I'd go off-road.
Some say you are less visible to drivers (I say that depends on the bike and your equipment, helmet and clothes color)
By the way, did I mention you get no hand pain, butt pain or neck pain?
Check out the variety here:
Recumbent Bikes | Recumbent Bicycles | Recumbent Trikes | Tandem Recumbents | Crank Forward Bikes | Hobie Kayaks - The Bicycle Man has over 50 Recumbents In Stock to choose from the largest selection in New York State.