Hmmm....
1) Gear for four people in Sterilite boxes. Air tanks, Save-A-Dive kit, boat bags (if needed) or luggage cart (used this summer at Lauderdale-by-the-Sea for easy tank transport to beach.)
2) Small ice chest with cola, water, sandwich items. Also fruit, other snacks, bread, paper towels, trash bags.
3) A couple of folding chairs and a tarp.
4) Our daughters usually are our DJs.
5) Some idea where we can get air fills and barbeque.
6) The first aid kit must have sunscreen and bug repellent, Sea Gold and Swimmer's Ear. Sudafed and Claritin also help.
7) The ability to swap stories with other divers about the local conditions, visibility, flora and fauna, other notable sites, etc.
8) Somebody willing to stay awake on the drive home.
9) Somebody also willing to rinse the gear and put it away.
10) Most important -- a sense of humor