I thought the KW was a bit high, but we ran the electrical load through the Generac estimator. The elevation and using natural gas drives the output lower than the unit's 24KW rating. The estimator recommends the 24KW based on those factors (Fridge, freezer, 4 ton AC are the biggest loads).
The estimate included a pad from Generac. It's a pre-cast piece at $350. I've not done concrete, so I have to ask for help or just roll it into the install process. I also had them up the gas regulator to a bigger unit. Technically our existing is big enough, but we are planning to build a shop soon, and I want to be able to run a gas heater in it, so since they have to be working on the gas system, it made sense to upgrade that now.
The generator will be along our house's eastern wall (with the minimum stand-off distances). We are fortunate to have gas and electrical service at that corner of the house.