In Oregon there is no sales tax but they there is state income tax. In Washington we have sales tax but no state income tax. If you live in Vancouver and work in Portland, you will get whacked with both, so don't commute over the river if you can help it.
Portland is nice, but it is really small, especially compared to DC. This can be a good or bad thing, depending on what you like. One thing Portland has a lot of is independently owned restaurants and shops, not a ton of chains, and that is probably one of the greatest things about it.
One other thing: don't be that obnoxious east coast transplant that all PNW natives can't stand. No one cares what is better back east, be it food, transit, or whatever. Things out here are different, and we like it that way. No place exemplifies that spirit more than Portland.