If you really want comfort, go with a gel-saddle and a suspension seat-post. I would say get a suspesnion fork too, but that would probably blow your budget. I have a trek 7500 w/the suspension fork/seatpost, and it rides like a caddy. The gearing is more like mtnbike gearing than roadbike gearing, so mtns would be good too. If you can find a used one in your price range, I highly recommend it. O/w, agree with other comments, Trek & Giant are both good. The last comment I have, is if you have a Mtn bike that fits & is comfortable, why not just buy some slicks and see if that helps ease your ride. Slicks would cost less than a new bike.