Regarding Portland:
1) Virtually everything on the West side of the river is accessible via mass transit (red line from the airport will take you into downtown). There are numerous bike rental places along the transit routes but I have not used any. Are you looking for a cheap hotel? A historic hotel? The East side of the river is more residential and the most bike-friendly.
2) There is not an incredible "seafood" restaurant in Portland. Southpark is the closest and I would rate them as very good. However, there are many options for exceptional seafood in other restaurants. Andina, Paley's place, etc. will have exceptional seafood -when- it's on their menus. The Heathman is hit or miss but I prefer it over Jake's. (BTW, most guides to Portland will recommend Jake's seafood... IMO it's not worth the $$$).
3) Portland food trucks, Pioneer Square, various East Side neighborhoods.
I like the food and drink recommendations on this website -->
http://www.portlandfoodanddrink.com/