Tom, you've gotten a lot of good info here. The site that NVSB4 gave you is very good. And the Butler maps are generally thought of as the best. They are available in many bike shops and RV campgrounds, even in Georgia.
There are several B&Bs in the area. Try http://www.b&b.com
The Lost Maples State Park has limited tent camping. Its really geared for the RV and trailer crowd. But Garner State Park has excellent tent camping.
The Sisters are twisted and undulating for sure, but not as radical as the Tail of the Dragon. You'll probably find the Sisters much more relaxed but still keeping you busy.
You can get good food at Neal's Family Dining Room in Concan. There are other places to eat in Concan, but Neal's was so good, I quit looking.
And if you're in Leakey on a Tuesday at noon, stop at Chicken Earl's. This old guy owns a small motor repair shop, but on Tuesdays, he serves fried chicken out of a small trailer. He opens at 11am and is sold out before 1pm. Check the reviews on TripAdvisor.com
One stop not mentioned is in Medina at the eastern edges of the Sisters. The Apple Store has everything related to apples....clothing, cooking utensils, jellies, and pies. And very good burgers.
The GWRRA chapter NVSB4 mentioned (I'm also a member) goes down there for a 3 day weekend at least once alternating years or more. For the 6 times I've gone with them, we've always stayed at the Best Western Sunday House in Kerrville. Kerrville is a large town with most of the national hotel and food chains.
Blue bonnets and paintbrushes hard to say. I think they bloom for about 3 weeks between mid March and late April depending on temps and rainfall. Keefer269 probably has better info than I do.
Let us know when you're going. I'm getting hungry just thinking about it.
2003 GL1800/MotorTrike Adventure IDMWT#25x3
Ride often. Ride far. Ride safe and do much more of both.
Give a man a fish and feed him for a day. Teach him how to surf the GWOF and he won't bother you for weeks, maybe months
I'll be waitin' for you at the end of the road.
If everything had gone as planned, it would not have been an adventure.