Hi I had a cabana last summer. We did order food once and then a couple of drinks. I did tip and honestly I wasn't sure how much. We tipped $20.00 total at the end of the day!
We had a cabana last year. Our attendant took care of our food orders. We tipped her as we would a server- 20% of the food and drink bill. We did add more because she kept checking on us and got us more towels, etc.
We tipped both when they brought our lunch and another tip at the end of the day but I was there 2 days before Christmas so I felt like I needed to tip better since it was the holidays. Our attendant was very attentive and the tips were well deserved.