Camp Galileo
http://www.galileo-learning.com/camp-galileo/index.html
You cannot go wrong with Camp Galileo. This is my safe option and a camp I can always count on. Fun for kids, great counselors, and a nice mix of fun with kids learning something. It is a low key camp yet quite well organized. You get a newsletter early in the week with the schedule and all relevant information. At the end of the week, each child gets a "certificate" with a really nice note from the counselor, as well as a picture of the group. My children just love going there and always like their counselor.
Galileo starts in K I believe and goes through entering 5th grade. The camp runs weekly, which is great. They offer three different themes for the summer (one per week). You can take one, two, all three or even repeat some weeks. I have done that and my kids did not mind. The nice thing is that even though Galileo is popular, you don't need to sign up the first day it opens in January (though I would not wait till June). The other advantage of Galileo is that your child will find their friends from school, soccer, old camps there. It is very much a place to reconnect with friends as well as meet new ones.
Jefunira camp
http://www.jefuniracamp.com/
Jefunira is a two week camp. Like Galileo, it is a great place. Each summer the camp gets assigned a different Palo Alto elementary school (as does Galileo too). It is nice to get the change. This year, it is back at Nixon, which is perfect -- there is more green space and also more shade.
Similarly to Galileo, this is a very professionally yet also very friendly camp. They do all sorts of fun activities -- starting with a tie die tee shirt on the first day. The counselors are similarly well trained and lots of fun.
The last two summers, I have signed my kids up to both Jefunira and Galileo (especially my boys) to provide variety as I generally put them in camp for 4-5 weeks per summer.
Jefunira fills out quickly so it is best to not wait too much past February to sign up.
Castilleja summer camp
http://www.castilleja.org/page.cfm?p=261
After several great summers at Jefunira and Galileo, Castilleja was a great place to go next for my daughter. She needed a change, something new. Castilleja is a four week camp (so only two sessions are offered over the summer). It is a nice place to go for an 8+ year old. It feels a bit more grown up. Before the summer start, each child gets to choose and sign up for lots of activities -- several (5+ I think) per day (from sports, to arts and craft, to theater, to computer training, etc.). The kids belong to a "group" but they only meet parts of the day as a group. The rest of the day, kids go to their "classes". My daughter found that very empowering and it also allowed her to pick activities that really excite her.
Of course, the grounds at Castilleja, are incredible. The camp is as a result on the pricey side -- but they offer lunch there, which is nice and girls love this camp!
Sign up early as spaces fill up quickly there too.
Other camps I have heard good things about (but have not tried):
- Marine Camp in Redwood City http://www.sfbaymsi.org/ -- they take kids on the Bay, look at fish, etc.
- YMCA in Palo Alto http://www.ymcasv.org/paloalto/ -- they offer all sorts of camps
- International School of the Peninsula http://www.istp.org/podium/default.aspx?t=120229 -- nice to freshen up French or Spanish skills
- City of Palo Alto summer camps http://www.cityofpaloalto.org/recreation/news/details.asp?NewsID=137&TargetID=7 -- they offer nice options too, though may not be full day
