Action Acres (AA) has a PSP field in Canby, which is about twenty minutes south of Portland.(Linky
Battleground Paintball (BGP) is in Battleground Washington, about 45 minutes from Portland
Portland Paintball is an indoor field about 10 minutes from anywhere in Portland (I believe it's on the south side).
Sweet7 is a great series at BGP, it's a 7-man NPPL style tournament.
Action Acres has the Oregon Washington Entry Level Series for begginers. You can find it on there website.
Depending on what level you play, there is a great variety of teams. Steel and Shooters in (who took 5th place in XPSL this year) play at BGP. OCD plays at AA, and HavoK plays at Warpaint in Salem (owned by Dan Bonebrake)