My guess is a 26kw generator will use 1 gal/hr. Propane is around $3.00/gal, so to run that hog will cost around $75.00/day in the summer and probably over $50/day in the winter. To me that is big bucks.
When power is out for an extended period I run my dual-fuel generator long enough to run the refrigerator until the condensor stops running and and possibly a space heater to heat a room, at which time I shut the generator and heater off. I keep enough gasoline to run my riding mower and other yard tools plus I have gas in 4 vehicles I can siphon. I also have propane tanks from various grills and such.
I have a Westinghouse 5300 watt generator I bought for about $750.