So, Wondering just how much sunscreen to bring so you don't have to spend $20+ re-stocking at the resort?
A simple formula that worked for us:
1oz of lotion per person, per FULL day
2-3oz. of spray sunscreen, per person, per FULL day
1> You spend all day (early AM to sunset) outside
2> You swim in the ocean / pool and need to re-apply often
3> You don't want to get burned at all (adjust the spf if you want to tan some / a lot)
4> You go AN so you have some extra bits to cover
We would use the lotion first thing in the morning and early afternoon for a complete cover up - usually in the room so we weren't sweaty.
After a swim, and throughout the day we would spray each other as the spray works best when you're sweaty or wet - mostly our shoulders & backs.
For example - staying 4 FULL days (6 days total)?
Buy 1 8oz. bottle of lotion, and 2-3 10oz. spray bottles.
My wife also likes to use the "Clear Face" lotion for her face - those go a long way and 1 bottle was more than enough.
One other note - keep your fellow travelers in mind when you start spraying - unless you keep the sprayer very close, it goes everywhere - We always tried to move away from people before starting.