Get as much equipment tossed in with the RV that you can. A few things to consider if not supplied:
A Progressive EMS to make sure the power coming into your RV is good. Campgrounds often have low voltage, surges, etc that can fry your electronics. Lifetime replacement/repair. Progressive Industries
Electric adaptors. If your rig is 30 amp, you'll want an adaptor for 50 amp plug and 20 amp plug.
Water hoses, I keep a 25' and a 50' for hook up. If you want a pressure regulator, get an adjustable Watts or equivalent, not the cheap water 'restrictor' regulator. A third hose, not for drinking, to be used for black tank rinse, car wash.
A good tool kit, with fasteners, multitester, replacement fuses, etc.
If you know what appliances and features your RV is going to have, you could spend time Googling their manuals and becoming acquainted.
Anticipation is a big part of purchase and waiting, dream and enjoy planning trips!