I'm of the opinion that people worry about this way too much. It's not so much a question of whether you're going to miss something, so much as you'll be doing one very enjoyable thing (eating at Palo) instead of another. There is so much to do on board, that you'll never be able to do it all and you'll run yourself ragged trying. We've eaten at Palo on formal nights, on Tropical night, and just regular restaurant nights. I don't think there's any one night that's any better than another. I'd say pick a night and just go with it. There are two showings of each evening show, so you're unlikely to miss a show because of eating at Palo. I'd say that Palo is better than anything that goes on in any of the restaurants on a given night. Don't think of it as missing out on something in the regular restaurant. Think of it as those in the regular restaurant missing out on Palo....
If you don't get to do something that you really wanted, there's always next time.