A friend of mine just purchased (and had professionally installed) one of the 10k natural gas gensets with all the auto-start and weekly run bells and whistles. Their power goes out all the time, and usually it's in the dead of winter during some crazy storm scenario that starts bringing down trees. IMO, it was a great move, and the natural gas makes it a no brainer.
I just fell into a crazy deal on an Onan Pro 6,500 with electric start and idle-down. It's a contractor style w/ Kubota engine. Couldn't pass it up. Then days later, a brand new transfer switch system for under $100. Of course, now that I have all that, the power will never go out again around here. But like techntrek says, fueling this thing......mmm, might be ridiculous.
I had a Kubota diesel on the generator in my yacht. It's a very cheaply built diesel and hard to get parts for (at that time) but I found it incredibly
reliable. A lot of people bad mouth the Kubota deisels but mine ran 1 hour a day, every day for 9 years (to cool down the cold-plate fridge). In that 9years, I sent he injectors out for service (mine was a 2-cyl) 3 times, changed a head gasket once, changed the oil every 100 hrs and never touched it other than that. To my knowledge, the current owner is still using the same engine (20 years after I bought it).