I've never been to the PNW, but I hear it's pretty great with the exception of the Seattle Freeze where people are impossibly socially awkward making it impossible to make friends.
I have never lived in Seattle, but I have visited several times and I found the people to be great. Warm and friendly. The city if very progressive with a ton to do. I have friends stationed there who didn't want to go, but ended up putting down roots because they liked it so much. Comes down to opinion of course... I live in Hawaii and there are people out here who hate it (crazy, I know).
In your decision, take into consideration the mission you'll be doing. If you don't care one way or the other, then so be it. But, D7 will deal with a lot of AMIO. Whilst D13 will primarily be fisheries and SAR. Also, you'll be getting the snot kicked out of you in the PNW on an 87', but hey, that's part of the adventure!
I was stationed in D7 (Islamorada, AIRSTA Miami, HITRON) for 9 years before finally getting back west. I definitely prefer the west coast; it's rugged, scenic, and wild. I like the cities and the people. I've spent time in Port Angeles, and it is quite beautiful. It is however quite isolated, so keep that in mind. If you're married and you and your spouse are into tearing up the town and big city living, then I would probably take St Pete. If small, craft breweries and farmer's markets are more your speed, then PA is where you wanna be.