I'll be in Austin this weekend and am looking for a hilly 10 mi route. Will be staying in SW Austin, but would be with driving some. I'm training for Pikes Peak so the steeper the better.
If you don't mind running on the big wide shoulder of a large road (I've never felt unsafe on it), then you could park at the bottom of Jester, run to the top and loop around at the end of Jester back down, then run up 2222 to Bell Mountain and do the same thing. Should be about 10 miles with some very good hills.
Also, at the end of Jester there are some hilly dirt roads and trails, which can get you at least an additional 3 miles, but they aren't well marked and it could be easy to get lost. Of course, that might be okay, to help you get to 10.