Rolling Hills, but if you go clockwise you'll have the big hill up Limecreek Road to contend with. It's about 250 feet of climbing in a 1/2 mile. Very scenic though around Lake Travis and the roads are typically pretty low traffic.
Rachel Ridge Park is where the map is set to start from, but Deer Creek Elementary School is another location you could start from.
Since it's a circle you can go either way. I think going clockwise is a bit more difficult as it has the hill up Limecreek Road. If you go counter clockwise you'll have the hill up Twin Creeks to contend with but it's about 100 feet shorter.
There's a couple cafes in Volente and Volente Beach has snacks.
Just in Volente
Spin City Cycle is the closest on the corner of Anderson Mill and 620, in the shopping center across from HEB (behind the Jiffy Lube).