Bluff Creek Ranch is about an hour to an hour and a quarter from Austin and offers a wide variety of trails. Bike rentals are also available on site, so if you are riding with an out of towner, you can have a bike waiting for them when you arrive. The owners are very friendly and there is bike repair on site and they can really come through in a pinch.
Trails vary and are all well maintained. Imagine the best flowy singletrack of Roacky Hill but without a Fat Chuck or Ike's Peak. No jeep trails either for the most part.From a challenge standpoint, it's a little less challenging than Rocky Hill Ranch but still offers a wide variety of diversions on the trail to keep you interested. If you are taking an inexperienced person out, this is a great place, and if you want to just ride sweet singltrack as fast as you can, this is also the place for you.
Location: Warda TX, ~10 miles east of Rocky Hill Ranch
From Austin, take 290 East, then 77 south when you get to Giddings. Turn Left (East) on Owl Creek Road, it's about a half mile up that road.
Technical Level: Medium. Definitely a good place for beginners, not too many technical areas, easy to maneuver. There are option paths around some of the more technical areas.