I bring it to the plane and let the staff put it in luggage for me. It's different for everyone, but I'm into smooth, peaceful travel. A car seat, for us, is anything but that.
Bravo for at least gate-checking the car seat! It's no guarantee but better than luggage-checking it.
Some of this might depend on the design of the car seat. I have no problem with the Radian. There are some seats which are better for travel than others. I've also used a Sit & Stroll (not recommended unless you do a lot
of flying like we do), the Scenera and I've also heard that the Combi Coccoro is a great, hassle-free seat.http://www.combi-intl.com/Products/Item.aspx?Item=12
I don't like to recommend buying a car seat for this purpose, especially for the one-off vacation. The seat most have in their car is probably already approved, but for those of you who see a lot of flying in your future, or who have had a bad experience with a bulkier seat, you may want to look into the subject further. If you are planning on purchasing another seat anyway soon, you may want to keep it in mind. I wanted a SnS instead of a dozen more baby outfits so my family pooled and got it as a second-baby gift.
For the record, I found that the heavier Radian easier to fly with than the wider, but lighter Scenera (I do admit I had an older model). Don't flee from the heavier models. If it's well-designed, sitting on a luggage cart, you wont really notice the extra weight.