We stayed at the Hotel Martinez and for our anniversary decided to book Palm d'Or restaurant (2 Michelin stars). There is a lovely terrance there, so make sure you book your table in advance to get the best place & view. There 2 types of menu available: a la carte & tasting menu. We chose the 2nd one. It was quite pricy (185 euro per person without wine), but the food was very tasty and beautifully designed. The only downside of the whole process was the time of the service.... it took us 3 hours (!) to complete the dinner and by the time we left I was nearly sleeping in my plate. So don't expect it to leave early :). Also for me the quantity of food in the tasting menu was a bit too much, I was feeling full at the 4th course.
I do recommend this restaurant for a special occasion: it is very romantic. Please make sure you are dressed up, otherwise you will be feeling acward.