The past 3 RV I owned had both. When I am paying to camp I use the camp grounds electricity, but if I am stopped at a rest stop whether it be sleeping over night I can take a shower in the morning or if I just stopped a few hours to cook a meal and take a nap it's nice to be able to have hot water using propane. If you are stuck with just an electric heater you are going to have to run the generator for hot water
By the way I just picked up a new (2009) RV that has 4 electric switches, the way it works is all 4 switches must be on and turning off one switch turns it off.
