Hello, I am asking for some help on an Avalanche, 05 that I am looking at. I want to know about leg room in the back. I have 2 teens and in a s/cab the leg room is inadequate. Will I gain leg room for the passengers in the back half of the cab or just tough it out with a s/cab...

I own a 04 F-150 Lariat which is loaded with leather, heated seats, sunroof and don't care for the leather etc.. Leg room is more important.
Thanks in advance...