National Geographic has the best travel photography anywhere and they work really hard to keep their standards very high. I've been to a talk given by Nat Geo photographers and learned that sometimes they're on assignment for MONTHS, just to get that one photo, or 5-6 images that accompany a magazine article. Amazing dedication (and huge travel budget).
Every year Nat Geo has an amateur travel photography contest, which I enjoy following. The contest ends next month, but some of this year's competition is worth a look at this link.