Yeah, diesels don't seem very cost effective for intermittent personal use. The triple fuel models might be a good choice, especially for a city dweller. More expensive of course.
We were looking at the triple adapters just the other day when I was cleaning carb on Honda (youtubes),advantage...can plump into home NG,or propane tanks or gas.
Propane stores forever.
Adapter kits around 200,but dont quote me on that,info could be outdated.
Edit,there is a place online that does the adaptation when you purchase a new genny from em,ready to go!