You money will go furthest in Portland, but not by a massive margin. I've never been there, but I considered moving there and did a cost of living calculator.
From what I understand, Portland (someone else can chime in here) is supremely left-wing. While I lean a bit left of center myself, some say it is a bit excessive and can cramp some of the car crafting lifestyle; getting flipped off for having a diesel or an old car, fines if they find aluminum in your trash, etc. I could be wrong, just some anecdotal things I've heard.
Seattle is wonderful. It isn't as rainy as you have heard... in fact it gets less volume of rain per year than NYC, it's just that its climate is similar to the UK and there are many misty/foggy/wet days regardless of how much rain actually falls. Seattle will be a touch cheaper than L.A. and there is a great maritime culture there.
I lived in L.A. for 6 years. If I could have afforded to stay, I would have. If your job/career pays a good salary, it is fine, but I was a bartender/actor/custom car shop fabricator. $1500 per weekend behind the bar, $2000/wk at the shop, and occassional $1000 contracts for acting didn't cut it. Seriously. Expect a small townhouse to run you $2700/mo minimum. 2 bedroom house, more like $3200. There are cheap neighborhoods, but you'll likely either not like the surroundings, or you'll have too long a commute.
regarding the L.A. commute, I honestly didn't mind it. L.A. drivers are fast and they're jerks, but they are GOOD in general. The only time I minded the commute was when I lived in Pasadena and worked down near the airport. If I didn't leave at the right time, it was a 1.5 hour commute for about 17 miles.
Don't listen to the hype about Smog inspections. They are only every two years, and the limits are pretty generous. If you fail smog in a stock vehicle, something is really out of whack. We Impala SS guys out there had a sorta rule of thumb; you could double your HP and still pass with careful tuning. If you needed more than 500hp, you just kept a stock engine sitting around and every two years you swapped it in to go get it smogged and then swap it back out. There is also no safety inspection in CA, so you want to go full race suspension? Do it. Now that I'm back in PA and I get yearly smog AND safety inspection, I miss CA. The DMV in CA is a big paper-pushing bureaucratic institution with a lot of red tape.... but it is well-organized red tape. I found it pretty easy to navigate the ins and outs of getting titles and registrations.
And, oh god, that SoCal weather. I joke with people about this but it is almost true. You get 48 weeks of 72.5 degrees and dry, breezy sunshine, then you get two weeks in February that it's 55 degrees and two weeks in August that it's 95 degrees. Sprinkle in a nice rain once every couple months and you get the picture.
You'll find that Beef and Pork are relatively inexpensive there since it isn't far north that there are massive feedlots. Milk and eggs are a bit pricier since they come from farther away. Produce is cheap. Something like 70% of the US's produce comes from CA.
And you know what the biggest thing I miss about L.A.? Avacados. Fresh 'cados picked daily at 4 for $1. Cripes, sometimes they are $2 EACH here in PA.