A couple of fast, non technical descents eastern part of the East Bay:

1. North side of Palomares - several different loops possible
2. East side of Patterson Pass - A couple of possible loops from Livermore are -
A. Old Altamont Pass Rd, Midway, Patterson Pass, the Flynns.
B. Patterson Pass, some flat riding south in Tracy, then back to Livermore via Corral Hollow (which ends in an easy descent back into Livermore).

A bit more technical, but always a blast, the south side of Morgan Territory Rd. A classic loop is Mt Diablo and Morgan Territory (or Morgan Territory and Mt Diablo depending upon where you decide to start the ride). That loop gives you both the Diablo North Gate descent mentioned above and Morgan Territory Rd south.