When we were relocated (employer paid for moving) last year, someone mentioned to me that I needed to feed the packers/movers. I was shocked and never would have thought of it, but asked the moving coordinator who I was working with (who worked for the moving company, not DH's company), and she said it's not necessary but is appreciated. I figured that if they had to get their own lunches, then that would be extra time away from my house, so by bringing them lunches, they were able to work more of the day.
I had them for 2 days of packing, 1 day of loading, and then when they got to the new house (in another state), 1 day of unloading. I fed them subs twice, fried chicken once, and pizza once. I also had Gatorade, water, and soda in the refrigerator for them. It sort of annoyed me to think of having to feed them when I heard about it, but once I met these men and saw how wonderful they were, how careful they were with my things, and how hard they worked (in the hot south Florida summertime heat), I was happy to feed them. I got lucky - they were such great men. I also tipped them at the end of the move, but I can't remember how much. (It was complicated when we got to the new house, because there were 2 new guys to help with unloading the truck. So I think I gave the new guys like $10 or $15 each, and the guys who had been with me for the whole move got $50 or $60 I think. I know that sounds like a lot, but they had been with me for 4 days, so that would have been $15 a day.)
I know it ended up being a lot of money for the food and tips, but I felt like they totally earned all of it with how hard they worked and how nice they were to work with.
Good luck with your move!