Some people will probably think I am crazy here but Santa Rosa is the most fun skatepark I have ever been to. I have traveled around Oregon, grew up in SoCal and now live in NorCal. I have had access to lots of great parks but nothing beats that place. You can go in a straight line all day and not even pop your tail and you would still have fun.
edit: I will admit that I would probably get tired of it if it was by my house because you can't really grind anything, can only do lip tricks in a few spots, there are no ledges, etc., but if you only visit every so often it is a blast. When we go there we often spend 6+ hours there. You can BBQ which ads some fun to it as well.
Not crazy, Santa Rosa is rad. I was thrown off the first time because I thought I'd be able to hit the place like Tommy Guerrero but learned quickly that the place is pretty tough to skate, but the second and third times were a lot more fun.
I was gonna comment about not being able to grind but saw the edit. I do like lip tricks but there's plenty of fun to be had at Santa Rosa regardless, just gotta go there in the mood to huck huge ollies or get tech on the more mellow spines.
I think one of my all time favorite parks is still Paradise Valley AZ, though haven't gone in a few years since they started charging and enforcing helmet rules.
Even crazier than Santa Rosa, I gotta say that Ben Lomond/Highland in the Santa Cruz mountains is still my favorite park. It's small, simple, but the bowl is a blast and I absolutely love the funbox. Perfect size and ideal inclines on both sides. Same deal, you can BBQ next to redwoods and there's a creek on the other side of the park.
If I could have a trip to skate any park though it would have to be Marsielles, with Burnside coming in a close 2nd.