I don't quite understand the differences between the advance purchase, fun fares, promotional fares, internet one way, etc. pricing. I click for a description but I don't really see any differences between them. Are there any I should avoid??? Of course I lean towards the lowest price but is there a reason I shouldn't go with those tickets. We would fly out of PHL if it means saving us some money. Spirit out of AC right now is 124/each way and SW out of Philly is as low as $79. They also have more flights then Spirit and we can play with times to get more time out of our vacation. I've never flown out of Philly or on Southwest before, can someone please guide me thru the process please!!!