Not too much we can recommend without knowing a lot more about what you like, don't like, etc. And you probably don't know yet. I'm sure some of the more "life experienced" folks around here can provide some useful tidbits, but you might just have to spend some time traveling to a few bike shops to try as many different styles of bikes as you can. I'd even try a recumbent to see how that feels... should be more comfortable than a standard road bike. I've seen a lot of older guys putting some serious miles on those. I tried one for a while for my back and it was great. But not so much for commuting in a city environment so I gave it up. If I was out in the country I'd totally have one.