The guidelines at Palo are "jacket recommended; no shorts or jeans please."
Sometimes on this board, people suggest that Palo is a very formal restaurant that you should wear the suit or tuxedo that you brought for formal night. That's fine, if that's what you enjoy. But it really isn't necessary.
Actually, Palo is sort of a "smart casual" place, like California Grill or Flying Fish at WDW.
In Hawaii, dressing up for dinner in a fine restaurant means dress slacks, an aloha shirt (no tie), and a summer sportcoat. Something like that would certainly work for tropical night and for Palo, especially if you're going to Palo on tropical night. Have fun, and don't worry about it too much.