For CS, Physics is probably better than Chemistry, but I’d take the one that interests you more. I also wouldn’t worry about the free period causing problems.
Washington is a WICHE state, so you’ll be eligible for WUE tuition exchange. Oregon State and Utah both have good CS programs, and would be good safeties. The under the radar option is Cal Poly Humboldt. Humboldt State just became the third Cal Poly, giving the degree more cachet. It’s a pretty campus in a pretty area.
Good luck!