PDX is a great airport. You should have no troubles with security, and the terminal where NW is small enough you can go end to end in 5 minutes tops. Nice new WC, may get a bit crowded with the NRT flight, but that might mean you have someone sitting next to you.
The Embassy is fine, near the airport, but I do like the new Aloft which is maybe a minute further from the airport. If you don't mind going further away, the Hilton downtown is great, the executive tower in particular. I've not taken the MAX, but heard good things, and if my clients were near the line, I could avoid the car rental. Its very close to the Hilton and countless other properties downtown. Downtown Portland is a nice area, and I encourage you to stay there if you have any time to spare.
Good luck