Okay, here's the deal. My friend is going to be taking a trip to LA to go to Disney in Feb. She has a 3 yo son and 1 yr old daughter. She wants the son in a seat on the plane, but is carrying the 1yo on her lap. She is going to take her Cosco Touriva on the plane since her son still fits in it, and her daughter will use it in the car in LA. But, she needs a seat for her son while in LA. He's too small IMO for just a booster, but can use the Ultra CarGo or something similar. He's 31ish pounds and 39.5" tall. He's all torse mostly, but very tall. What do you suggest?