There's a book by Andy White, "Best Bike Rides- Texas", that's fairly worthwhile. Not showing up on Amazon, for some reason, there's some old green version there.

For Oklahoma, there's a bicycle club in OKC that has some rides listed on their website if you can google them up.

For charity rides in Texas, go to the Texas forum, look under the "Texas Rides" sticky, and I've got a couple of websites that keep track of charity rides.

It might help to say where you're going and what you like to do.