Paying to check a bag: I like to check my bag. I know it's annoying to stand in the longer line and there's always that gamble of whether or not your bag will ACTUALLY be there to meet you on the other side. But I hate maneuvering onto the plane with a biggish bag and I hate fighting people for overhead bin space. Also, this one time I hoisted my mini suitcase up to try and stow it into the bin and it was ever so slightly too big. I nearly had a panic attack as I tried to grapple and shove the bag into the bin with the increasingly impatient LINE OF PEOPLE waiting behind me to get on the plane. Fortunately the flight attendant came to my rescue saying "the bins on this plane are slightly smaller than most, I'll find a space for this." OMG hugegiantsighofrelief.
Anyhow. If you, like me, like to check your bag and if you, like me, hate paying fees for it, try this: Pack all your stuff into a little carry-on sized bag. Go through security. Go to your gate. If the flight is mostly full they will likely run out of bin space and start making announcements BEGGING people to check their bags. So you will not only avoid the $20ish fee but they will actually thank you for checking your bag. I've done this on both Virgin America and Jetblue. Maybe it sounds like more trouble than it is worth but it is worth it to me.
Forever 21 returns: You know how if you buy something at Forever 21, you only get 21 days to exchange it? Well if there isn't anything you want to buy the day you go back to exchange your item, have them put the credit on a gift card. Not as good as getting your money back but doesn't expire so you can forget about the 21 day window.
Okay, that's all I got. What loopholes do you know?