This will be my son's second flight, but first with his own seat. He's 2 1/2 years old, but big for his age (39", 36lbs, wears 3T-4T depending on brand). My wife and I are still going back and forth on whether he should sit in his car seat (Britax Marathon) or in the seat with a CARES Harness. I've read up on both options, but still unsure which way to go. It sounds like the car seat would be more comfortable, especially for sleeping (which he might do on the flight there since it's his nap time), but I am concerned about him kicking the chair in front of him and not being able to use the tray (coloring, playing, watching movies, etc.). With the CARES harness it sounds like we would still be able to use the tray and would not be able to kick the seat in front of him (not that he's likely to do it anyways), but may not be as comfortable for him sleeping wise.
We will be bringing both and if we do check the car seat it will be at the gate, so we pretty much have up until the last minute to decide.
I would appreciate any thoughts, suggestions, or previous experience.