Costco ice cream

I need to buy ice cream for 300 middle schoolers plus staff. I stopped at Sam's Club today since we have a school account. The vanilla ice cream is in 1 gallon, 1 pint containers. The ingredient list is, IMNSHO, icky. I can go to Costco tomorrow, but before I brave Oakbrook at rush hour, how is the ice cream packaged, and more importantly, is it good? Or at least better than Sam's? and can I get sprinkles and toppings and lots of 'em? I can also go to GFS. Schweppes if I absolutely have to. Vanilla ice cream only is fine.

And how much is a serving anyways, because it sure isn't 1/2 cup around here.