With my wife's work and the kids daycare being an hour away, the schedule doesn't really allow time for a dealer. That, and what they charge, I can afford to try a few things before I get it right.

I rode in the back yesterday, and the skwook sound seems like it's coming from the back right, not the front. Is there anything other than a shock that can make that sound? Can the leaf spring do it?

The creak in park appears to be separate. I can get it to creak before driving, but it's not as loud.

 

I ordered new rear shocks. Monroe Sensatracs. If I rock the van side to side from the outside, I can recreate the noise. Definately the rear. And contrary to how it sounds inside, the left is louder from the outside.
Even if they aren't the problem, shocks are cheap, even decent ones, and easy to replace. And with over 125k on the van, it needs them anyway.

 

The rear shocks were the culprit of the "sqwooking". All better now.

There is still a creak coming from the front somewhere, but it's not evident while driving. While I was working on it today, I also did the front sway bar end links. It gave the opportunity to wiggle and spin stuff. There was a rubbery squeek that seemed to come from where the driver CV mates with the transmission, only when spinning the driver wheel very slowly forward. Spin a little faster or backwards, no squeek. It sounded pretty much like the squeek when I rocked the van fore/aft, just less harsh. I sprayed some wd40 there as a test and the squeek stopped. Should I suspect an issue with the trans output shaft seal?

I also found that the passenger CV has a slight wobble or bend, and the tie rods have just a bit of play.