I will second Tom on that, what are you running.. If all you plan on powering is a 60 amp converter. 1,000 watts, 80 amp converter 12,000 -14000 watts. (I've done it with a 1,000 but the generator ... Well let's just say it's rating was a touch conservative)
Television: CRT color add 300 watts, LCD around 150, Plasma perhaps 500 plus don't forget the starting surge on that crt (I don't know about plasma)
Microwave add 1,000 watts
Air conditoner add 2,000 watts, Fridge 400 (350 actually but leave overhead) water heater 1300-1500
Just add it up, don't forget a KW (1000 watts) for the converter/battery charger and... That's it.
NOTE Air conditioners do not usually draw that much power.. but you need to add more due to starting surge
Next you get to what to buy.. HONDA inverter units can often be run in tandem There is a serious advantage to this in that unless you need full power (2 x 2000 watts = 4,000 watts) you can shut down one for re-fuling while the other runs. and also you can use just ONE if you don't need 'em both saving on fuel that way Plus if one should fail you are not completly SOL as it were while it's being serviced.
Some practical information
I have a 38' class A. 2 converters (80 and 100 amp) When I'm here at home I plug it into a 20 amp 120 volt line (2400 watts) that is enough to run ONE air conditioner OR the water heater it runs the Microwave (Though if the A/C kicks in while the Microwave is running it can cause the click of darkness) I currently 100-1650 watts of heat along with the converters (Since batteries are full up the converters are sucking idle current and a little bit to run some radios and constant loads and one light)
Now if wife goes out in the summer and turns on an A/C and the water heater.... CLICK
During the summer I may plug into 30 or 50 amps depending on the site.. 30 amps I can run the entire rig, save only one air conditioner (So I split the other one off and plug it in separate from the rest of the house 30 amps is 3600 watts
Of course where I like to park, 50 amp sites. that 12000 watts (Something look strange about that math.. it should The voltage doubled)
IF you can manage the power I'd go with a 2400 Yahama or a pair of 2000 honda's