Frontier Airlines announced a flashy deal for frequent travelers Tuesday: a summer travel pass priced at $399 that will provide unlimited flights anywhere on its route map for nearly five months later this year.
It comes with big catches — several of them costly — that make the promotion the best deal for the most flexible of travelers, especially if they travel light, with no checked or carry-on luggage that would incur fees. The returns are likely to be diminishing for others…