My experience with RRG is a bit limited; as I've only climbed there a couple of times. Best bet is to get the guidebook, which is available at most outdoor shops in the area (at least 2 stores in Lexington, and it's probably at Miguel's Pizza). Otherwise, I know that Muir Valley has a good concentration of beginning-level climbs, though it's likely to be crowded (popular area).
30 feet of webbing is a fairly standard length for setting anchors off trees. Luckily, you'd be hard pressed to run out of bolted climbs.
Hope this is helpful,
-Colin Pizarek