When I had my shop built, I kept plenty of iced non alcoholic beverages in a cooler, as well as bottled water. The bottles are better because they are easier to drink part of and then cap off and then too they don't blow away in the wind and make a mess. I also bought lunch a couple days, like pizza's subs, etc. Some other things that I would do is keep several large 55 gallon trash barrels around the job site. That way if they have something to throw out, a trash can is always nearby. If it's real hot out, a shaded area with a picnic table might be a good idea. Having a shady place to eat their lunch is surely welcome.
Facilities.... some areas require the site to have a porta john, on site when you get your building permit, and other areas don't. Make sure you provide either a ports john, or let them use your house bathroom (not recommended) or something on site... IF a porta john, I'd also recommend a portable sink or somewhere to wash up..
I had one crew during one construction phase that left their lunch trash, bottles, wrappers, etc and cigarette butts strewn all over the property... They didn't get the pizzas for lunch!