Check out active.com. I find many of my rides and 5k's on their site. At least in the Atlanta area, most charity rides offer many mileage levels. One I'm riding in in a couple weeks offers 28, 40, 60 and 100 miles routes... something for everyone! Glad to hear your looking for a ride!
Most of the charity rides (and 5k's) are usually around $25. At least in my area.
Cycling... If you're not having fun, you're doing it wrong.