Track days in Northern California?

You can pretty much choose any t rack day event you like. We do it here on the east coast up at NJMP. Be aware there are some expensive cars on the track, choose who you want to be racy with. Or are you talking solo type runs?

Not solo runs, regular track day type stuff is fine, but there are at least a couple here in NorCal that explicitly say "No Lemons/Champ cars" which I sort of understand, especially if someone is out in some expensive car, as you said.

I do track events at Sonoma/Thunderhill/Laguna Seca with the follow groups (in order of preference):

Trackmasters
Golden Gate Lotus Club
OnGrid
Turn8
NCRC
DriveTrackTime

I know the groups you're talking about. NCRC is one of them. They're a bit pretentious about who runs with them, but they've let me run in the past. Just today I reached out to SpeedSF about letting me run with them. There's a third but I forget which it is.

In general I understand some groups' reluctance to let hot garbage out on the track. A lot of groups will black flag a whole group if there's a breakdown, which kills time for everyone. So if you have a total heap they don't really want you out there. Likewise if you're a total newbie signing up for open passing right away. Or hella slow trying to run open passing with much faster cars. But I think if you reach out and explain that you're not a knuckle head, there's a decent chance they'll make an exception.