I see that Austin Cycling Association has a 9:30 am Saturday ride from MJ's. Look here for a description. Guaranteed not to be a hammerfest and will give you a nice tour of the city.

Also, it looks like the "standard" ride from Bicycle Sport Shop on Lamar (not far from you) is on for an 8:30 start, although you might want to give them a call to see if they're going to slip to time a little later due to freezing temps forecasted. It's a rolling ride with no steep climbs, in the 25 - 35 mile range. Their events calendar is here. I would not catagorize any of the Violet Crown rides as "base"...those guys hammer, as do the guys from Austin Tri-Cyclist.