Easy way to find something as a starting off point is to enter the date on Open Table with parameters that you might like. I'd steer clear of Chinese unless you are looking to re-enact A Christmas Story scene. <G>
Quick look brought up many places. Some non-hotel choices are: Charlie's Crab, Nick and Johnny's and Renatos. Some don't open until 6 p.m. I use Open Table more and more as they get greater traffic than Chowhound these days. There are enough discerning palates that use their service to get a handle on what a restaurant might be like. You won't get Chowhound dive recs there however.
I like Renato's A Palm Beach favorite for many many years. Lovely ambiance.
Nick and Johnnies appears to be part of a local group of restaurants. More casual. Search here, read reviews here and on Open Table, maybe Zagat.
Charlie's Crab has an ocean front location (looking across the narrow hwy). It has been in Palm Beach for at least 40 years. It might be an interesting sociological study, the old money white shoe Palm Beacher in his habitat (Renato's has similar clientele, or at least it had when I was last there)
I'm not familiar with the WPB area but, if it's like every other place in the US Christmas day, your best bet is to find a really good Chinese restaurant. That's become our traditional Christmas day lunch because there's nothing else open in the area of SE PA where we live.