I provide the wipes too but always treated sunscreen the same as diaper creams. Each child has a bin with their changepad in it and whatever brand of diaper cream parent wants in it and we have a bin at the door with all the sunscreens in it. I don't find it takes much more time to switch bottles since I put it down to rub in anyways and then just pick up a different bottle when I move to the next child.
Would be interested to know what brand you are most happy with Judy. I do not allow the sprays that get everywhere since we are doing the lotion as a group at the door. Even the other sprays I usually do it into my hand and than smother it on the child rather than spray on the child and rub in. For myself and my own kids I have Ombrella spf45 or 60 when I can find it cream lotion and that is the only one my red headed kids don't burn right through.