Question
We live in Marin county, just north of San Francisco in zip 94901.  We have an area prepared for sod, but the soil is only about 6 inches deep with rock underneath.  The area is in the sun most of the day, but does get some shade in the morning and late afternoon.  It's also close to a large pine tree so will get some needles on it.  We are wondering what type of sod might work best, especially with the shallow ground.  Thanks for your help.  

Answer
Most grass roots grow in the upper 6-8" of soil, so any sod you choose will do well. Kentucky bluegrass would be a good choice and commonly available as sod. Perennial ryegrass require above normal water, and fine fescues would do poorly in your full sun.

I recommend either kentucky bluegrass, or tall fescue. Personally I like Kentucky bluegrass a lot.