Welcome to Northern California. I don't have a junior girl for you to hit with, but have had some experience sending my kids to clinics on the Peninsula. There are a number of choices, but two that tend to get quite a few kids are:
Player Capital http://www.playercapital.com/Juniors...edule-2013.php
and Eagle Fustar: http://www.eaglefustar.com/ef/programs/
My kids did both at different points. I liked Player Capital because the locations were easier for us to get to, and the times were more convenient. Mike Jessup is also an amazing teacher from a technical perspective (fyi, CiCi Bellis, who recently won her respective age groups for Les Petit Ans and AEGON Junior International trained here for awhile). That said, the competition is deeper, and a little older at Fustar. They also post quite a strong group of current and alumni players.
There are other, smaller programs in the area. Though we don't have personal experience, Kim Grant runs a program out of Winter Lodge in Palo Alto, which has a lot of younger girls.
The good news is there are lots of options. A number of the private clubs in the area (Palo Alto, Los Altos Hills, Menlo Park, Portola Valley) have pretty good junior programs as well.