Don't go with liquid propane. I had a 15,000 watt Generac that ran off of 250 gallons of LP. The smell was horrible and the gallon-per-hour wasn't anywhere what you would think it would be. At 50% load I only got about 20 hours out of 250 gallons of LP.
Actual liquid fuels I have found get better hour per gallon. In the previous post that you mentioned I said that I got about 12 hours out of 9 gallons of gasoline when running at around 50% load.
That being said 2,000 watts is a bit small for a transfer switch, but can be done. It certainly makes things easier than having cords strung about your house constantly. Honestly if you want a hardwired/pig-tailed system on your house then you should go with a generator that has a 120/240 volt 30AMP Plug. 3,000 or so watts.
As for where to get a good generator that's a Honda. Best place to look is equipment rental companies. They either have used models for sale (Which are as good as new) or models that are for sale brand new. That's pretty much the only place I have ever seen Hondas. Is either Honda dealers at Power Sport stores (Motocross, Quads...etc) or at Rental Supply Companies.
Hate to disagree with you Izzy-
I find it insanely hard to believe that a 15kw generator on propane went through 250g of propane in 20 hours, especially at 50% load. That's 12.5g per-hour, but they only fill those about 80% so 200 gallons for 20 hours is still 10 gallons per-hour which is no way possible unless it was way out of tune, even then I don't think it would work well at all if it was going through 10g per-hour.
http://www.amazon.com/Generac-4582-2-Portable-Generator-Compliant/dp/B00007J8CB"A large, 16-gallon capacity fuel tank give the generator a 10-hour run-time at half-load capacity" 10 hours on 16 gallons at 50% load. That's pump gas. If it were propane figure 19.2g OR it would not run 15kw depending on the conversion.
So, no way in 20 hours did a 15kW generator use 200 gallons of fuel.
Also, you are comparing a 15kW generator to one rated for 1.8kW. And also a Honda vs not a Honda
I think the propane conversion for the Honda rates them at 1.5kW not 100% on that. Also, every review I've read on-line from converting the Honda eu2k to propane has been positive. The only negative, and the reason I have not done it is warranty. Honda refuses to warranty their units if converted to propane