Hey Tanner its Randy. Your best bet would be around North Bend or Snoqualmie(not the pass, little town just outside of North Bend), while you are further from Index the trip to Levy is sub-2 hours, there is tons of mountain biking, kayaking and rumor has it that there are some boulders being developed in the area if you know where to look. Also, highway 18 would cut right through Auburn and into Tacoma for when you have to work down there. As far as Monroe goes... it may leave a fair bit lacking. Unless you were in Index proper I wouldn't really consider it, and at that point you are too far out. If you have any more questions feel free to shoot me a text if you still have my number!
Seattle's a great place but the suburbs leave a lot to be desired. Monroe is a little out in the sticks, and not in a "cool small town" sort of way, more of a "bunch of people who can't afford a house in Seattle bought a track-home and built strip mslls here" sort of way and there's a state penitentiary there. North Bend isn't necessarily bad but you live in a valley with an 8 lane freeway going through it. It's turning into suburbia as well. I lived in Seattle for 5 years and I think your best bet is to just live in the city. The gyms are good and while it may take a little while longer to get to L-worth or Index the things to do while you're in the city make up for it. Be prepared though, summer in the Northwest doesn't start until July 4th.