I had combined Seattle with a trip to SF / Oakland (flew between) and really regret rushing through Seattle. Still want to visit Mt Rainier and Olympic National Park too...

If you have time and the inclination on a nice day, Mt. Rainier is gorgeous in September. You can rent a car (pick up downtown) just for the day and drive yourselves---it is a little over 1.5 hours each way, barring traffic problems.

Yes, I've decided to do that.

Today I decided absolutely. I'm going to focus on a 6 or 7 day block of time (with the flights)just for the Seattle area. And we will rent a car for a couple of days at least for day trips.

I've been to other parts of the USA (SW and SE especially) many times and over decades, but haven't been to this part of the country at all. I've been to SF twice and we drove North- but not to Washington state.