Thank you Melanie - great info to have! I'm also posted on SF site - wanted to use Shuberts, but it's for a wedding on Sunday, I live in Menlo, etc. So this was very helpful as I didn't look up what a Princess cake was supposed to have. Likely many varieties on that....
Can't vouch for these personally, but perhaps someone else can. The two that come up from googling are at
Layers, and sounds classic with the Bavarian cream component
or Paris Bakery, which omits the custard and only lists whipped cream
Princess Cake (SF Bay Area)