United Airlines doesn't have a carry-on fee for any tickets. If your carry-on is bigger than the maximum permitted size, United will check your bag to your final destination (but you might need to pay a checked bag fee).
Flyers living near hubs, such as Atlanta for Delta Air Lines DAL or Seattle for Alaska Airlines ALK, are usually best served by those programs. What benefits matter most? For some travelers, it’s all about upgrades. For others, it’s baggage fee waivers and lounge acce...