You can't really ride a road bike on trails, that's what mountain bikes are for. I'd say get a cheaper bike with moutain wheels for recreation, but get a road bike to ride around town.
If you're looking for something casual, I'd recommend looking on craigslist for about any kind of bike. Trek bikes are usually best, but other brands such as Giant and Schwinn are good as well.
If you're looking for something more pro and specialized, try a Cannondale or a Terry.
Good luck!