OK, I'm a big advocate for the Rails to Trails program but then I watched one being built for 16 years. Of course, I moved 1000 miles away and they now have 87 miles of that trail completed. It was the Pere Marquette Rail-Trail that got me inspired to return to biking 11 years ago. Unfortunately, I had a bike that didn't exactly fit me, so I never rode that trail.
What I'm gonna suggest is, find a rail-trail and give it a try. I was gently reminded yesterday, when I faced a paved rail-trail, that there are inclines and declines. Surface will vary: Asphalt (my favorite), Crushed Stone, Gravel, Ballast, Sand. It's like riding thru the woods, they can be scenic. The lady I met on the trail yesterday, told me, I was in a "one horse town". Well yah, any time you ride a rail-trail, you may go thru some towns. That's what was nice about the Pere Marquette Rail-Trail in MI, it went thru alot of little towns and for me, I knew every one of them. Would have been easy to stop for some pie since some of the old rail depots are now actually restaurants.
Here is the link to the rails-to-trails conservancy website. They list current trails state by state. Just don't trust the parking & trail access info. I did that and had to bike 1/2 mile just to get to the beginning of the trail where I found a parking lot next to the trail.
http://www.traillink.com/