Have dealer show you how to manually retract your slide(s). Make sure ALL manuals are aboard or have the dealer download the missing ones. Have the awning demonstrated and make sure there is an awning rod. If it is motorized and has a remaining engine warranty, make sure the dealer has transferred the paperwork to you. Check spare tire (make sure it is usable and correct psi). Make sure the potty holds water. Turn on water heater and operate ALL faucets hot and cold and let them run a few. Check the location of breakers and fuse boxes and understand how to troubleshoot a power outage. Measure the tire pressure and test drive for alignment. Dealer should deliver you with a full tank of gas and propane.
A thorough pre-delivery orientation should take 2+ hours.
And like the previous poster said, have EVERYTHING demonstrated--not just presented!
And for heaven's sake, don't take it off the lot if items are not functional or missing. You WILL regret that if you do.