Having spent a fair bit of time in all three cities (including Houston), I would say my top choice would be Portland. It's a nice city, not too big and not too small, with a great quality of life. There has been a lot of major redevelopment in the area along the river and former railyards, and it has come around nicely. Some of the new suburbs are worth checking out as well. Orenco Station comes to mind as one (America's Community of the Year in 1999) http://www.costapacific.com/communities/orenco.html