Awesome!
I feel with the cities you’ve already listed, you won’t run out of things to explore. I find old cities with rich histories to be great for exploring, and I feel New England has it’s own type of weird that is worth a visit. Check out Providence, RI (an hour or so from Boston), take a ghost tour and learn a bit about EA Poe or HP Lovecraft’s time there. Plenty of old buildings and tunnels to explore.
Savannah, GA or Charleston, SC, down in the southeast corner of the country has some rich history, plenty of music, and a style of food you wont find many other places. Great place for haunted houses and ghost stories as well.
One state you may want to look into is Texas. It’s not a state that springs to mind for many, but there’s plenty of old ghost towns to explore, lots of taxidermy, and an established art scene, in certain cities/towns. Look into Marfa, Denton, or Austin. No shortage of metal/rock music there either.
Speaking of ghost towns, there’s a few in the Pacific North West (PNW) however they get overgrown fairly quickly, compared to those you find in the desert.
Do you listen to podcasts? “Last Podcast on the Left” is a great one if you’re into macabre, UFOs, cults, etc. Presented by a few comedians in NYC, it’s always a fun listen, and may give you some ideas of places to visit!
Have fun! And let me know if you end up in Seattle!