So glad to hear there's another 15 pounder out there who is flying. What carrier are you using? I actually bought the medium sherpa bag but it seems way too small for him to fit in comfortably. Someone recommended a Sturdi bag which I bought, it's size large and seems a bit bigger then the Sherpa. Only issue with the Sturdi bag is that it doesn't open on the top and my sissy boy doesn't/won't walk in from the side he gives me a hard time. Once he's in the bag he's fine. Timmy also uses a booster/bag in the car I think it's a Pet Gear. This shaped bag is more square and I'm going to measure it and see it I might be able to use that one since he's so familiar with it.
I use a Sherpa bag (size large, I think). It slightly exceeds airline sizes, but the sides squish which makes it okay. American actually says that on their website, which I've pulled up at the ticket check-in. Marlowe can sleep comfortably in there and move around without any problem (except when he decides to move to one end and throw me off balance). He's not standing at his full height, though.
The hassle is very airport dependent. Some airports, I never have a problem. Others, I always have a problem. I usually fly AA because of their prices on my most freq routes. I have a friend with a larger rescue mix pup (~18 lbs), and she never gets hassled leaving from our home airport, but always gets hassled on her return flight from her family's airport. It's awesome other places let you check-in and pay for your pets online. American Airlines definitely doesn't and it's the part I dread the most with flying with my pup.
And I totally forgot about getting your hands swabbed for residue. Last time, they were like okay I need you to give me both of your hands so I can swab them. Me - I'm holding a dog right now, how about I give you one at a time? Sigh.
Even on trips without my pup, I've started preferring to drive over dealing with the airlines. Like with most flights these days, it's everything up to passing security that's the most hassle. Once you're in the terminal it's not that bad. Oh and the $250 roundtrip charge to lose your leg room to your pup and then another $50 to check the bag you sacrificed to you pup - not to mention the hassle of everything - definitely make driving look like a more reasonable option. I don't balk at a 10 hr drive quite the same way since I got my Hav and flew a few times.