The commonly available woks are 14 inches in diameter. This fits reasonably on US home equipment. However, US equipment is not capable of supplying the heat to use a wok that size with much in it. Any bigger than that interferes strongly with neighboring burners.
You'll need to cook in small batches to get the texture, flavor and proper done-ness. So it doesn't matter how many you're cooking for, it just takes more small batches to recombine them for final heating just prior to service.
If you have a a high output outdoor stove, you can cook better on that in a wok than indoors on your home stove.
Something from these guys would do a good job.
Outdoor Stir Fry Stove - Home - Outdoor Cooking.
and a 14 is big enough to cook for 6 if you have the heat.