I have also been looking into purchasing a generator. Here is what I have found.
Blowers w/ the heat on will pull around 23 amps. If you take the 23 amps X 120 volts = 2760 watts. They require more to start up, but this can be minimized if you turn each fan and the heater on in slow sucesssion rather than all at once. Anyone who has had to endure the sub-par wiring in most cattle barns already knows this!
If you wish to run lights and clippers w/ the blower, the lights can be figured at their stated wattage and clippers only draw nominal amps.
If you wish to run fans also, these can be figured in the same manner based on the rating of the fan motor.
BTW, look into Harbor Freight Tools, they have the best rated generators at the best price point that I have found. And if there is a retail store close to you, you could save some serious shipping charges!