Weve got a Troy-Bilt, ~6K watt (9K start), runs about 10-11 hours at 1/2 load, nice chassis/tires, plenty of outlets.
That runtime is on ~8 gallons of gas, so youve need a decent amount of gas to sustain several days of continuous use.
Only used it one time for an extended period (about 3-4 days).
We have a ton of extensions (for Halloween/Christmas decorations), so it was easy to run lines in from the garage to the main fridge, a couple of fans, some charging stations for phones and computers.
Just ran it backed up, partially out the garage, with the door 1/2 open, plenty of ventilation.
Our gas grill came in super handy too, had a full tank so we were able to grill burgers, hotdogs, warm up things on the side burner.
They have models with electric starters and other features, more output, etc., they all run about $600-900, we scored ours on sale for about $400.