Within 4-5 hours of Portland, you have quite a few rivers to check out. The D would be a decent bet, near the mouth. Access is decent, but you won't be alone and it's HOT hiking up and down the many miles you need to cover. There are some options in Washington as well. There are some smaller rivers around, some with good access, other's poor, most have glacial problems and clarity can be terrible if the weather is extremely warm. Get good maps, call some shops, hire a guide when in doubt. There are many great guides out there and they are worth every penny when you only have a few days to get into good water. Give Tom Larimer a call, he's a two-handed dude who seems to guide all those Portland area river's and the D too. Have fun and best of luck hooking those wild chromers!