We do two distinct types of camping - full hookups and dry camping. Usually the full hookups in State parks in the winter and dry camping in the summer. I bought a Microwave for the camper 10yrs ago - its still sitting in the garage unused - we like the extra storage space but in winter months (plugged in) the little 800W unit might come in handy.
(factory/dealer installed likely comes with a HEAVY markup!)
My last camper I opted for AC on the roof. Since we're dry camping during the summer months it rarely (if ever) got used. I can count on one hand the number of times we used it. I did not bother having one installed on the new camper.
As far as gensets go, I'm a big fan of solar and inverter generators. Propane in my area almost always costs way more than gas and I'd rather save it for the furnace/Fridge/Water heater. I carry a little Yamaha 1000i in case the solar can't keep up. The other half has shown interest in having the microwave to use so I suppose the Yamaha could power that if need be.
Moral of story: think of how you do your camping and if you'd save money or even use the factory options - we use our oven all the time.