Hello!
We took a trip to FL with a 5-month old. We just used his stroller in the airport, with the carseat attached. We flew Southwest Airlines, which allowed us to take the carseat on board without paying an extra ticket, if the flight was not full. But the carseat was just attached to the stroller, which was very handy because of the storage space on the stroller. Then we just carried him on board in the carseat and his fit just fine. It is the Graco SafeSeat model, bigger than the Snugride. The stroller was collapsed and left at the door of the plane. I will warn you, however, that they beat the tar out of the stroller!
It was all fairly simple. It was nice to do it this way, because of all the security measures. He just sat there while we did what we needed to do, a security staff held him while I collapsed his stroller for the x-ray, then we plopped him back in it after it had gone through. Going through security was kind of a mess, but I don't think there's any way to make it less of a circus!
Best of luck!