If I were buying a new RV again, here's what I'd check:
Make sure everything work: oven, range burners, microwave(try heating some water in a coffee cup), refrigerator/freezer, air conditioner, furnace, all lights/switches, and electrical outlets.
Have them fill the fresh water tank so you can check pump operation. Fill the water heater and make sure it heats on electric AND propane. Check all faucets, including outdoor shower. Check that the toilet flushes correctly. Check for leaks in water lines when the system is under pressure. Make sure the sink and lavatory drain traps are attached tightly.
Open all storage compartments, making sure all doors operate smoothly, the locks work, and that the doors seal tightly against the foam gaskets. Get on the roof and check to make sure all the sealant work is done correctly.
Make sure the TV antenna can be cranked up and down easily. Hook up a television and check the antenna outlets and that the signal boost works. Check the sound system/speakers for proper operation.
Check all cabinets/doors for any problems.
Check the age of the tires (there's a date code on them). Tires are only good for 5-7 years, even if they have good tread left. Just make sure they didn't mount old tires on your RV. Have them make sure the lug nuts holding the wheels on are torqued correctly, and have them check and adjust all tire pressures, including the spare.
Make sure all the windows open and close smoothly, and that the blinds move smoothly too.
Remove the air conditioner cover on the ceiling and check that the 4 mounting bolts are tightened correctly. Many have been found to be loose.
Crawl underneath the RV and check the frame and any welds to the frame.
Well, that's all I can think of right now. I may come up with more later,
Edited to add: Or just read Healthi's PDI check list!
2011 Dodge Ram 1500 HEMI Quad Cab
2011 Jay Flight 26BH