The last time I was at PDX, I paid street pricing and no sales tax. The airports where I have eaten for reasonable prices: IAD, PIT, some concessions in PHL, SAT, IAH and others. LAX can be pricey it was worse before. Since LAX is one of my home airports, I don't generally eat there unless I get meal vouchers with a bump.

CLE seemed to have high prices & limited selection of eating places. ORD can be a little high now--especially since they took out the Panda Express!
A few years ago, I would find the Burger King at SFO (not easy to find but as close to street price and not expensive).