We've used these for kids and adults. These are various kid versions. I like the ones with the pushbutton sides (like the 2-pack and below) but the straw ones were great for non-spill, especially among the younger set. You have to suck on them to get the liquid. I don't think I ever had a spill (unless I forgot to seal it.)
For snacks, I do Z-bars, dried fruit, crackers (Teddy Grahams, Annie's or similar), grapes, apple slices, apple sauce in pouches, trail mix, mini-cookies (Oreo's, Nutter Butter, Nillas, etc. Costco sells assortments), cheese, juice boxes, chocolate milk boxes.