I strongly recommend you bring ear plugs for the noise, and don’t forget your sunscreen. In terms of lodging, I suggest Hotel de Paris in the winter, and in the summer, Monte Carlo Bay because of the unbelievable lagoon swimming pool with sand.
My favourite restaurant depends on what I want to eat, but I would say the Maya Bay for the atmosphere. If I am looking for a quick coffee break, I go to Cova in Boulevard des Moulins, which has the best Italian coffee and pastries. For a good night out on the town, jet over to Sass café for dinner and then to Jimmy’z nightclub. Yacht Club is one of the best harbour-side bars, but it is members-only. Alternatively, there is the Quai des Artistes. For some retail therapy, the Casino Gardens or the Metropole Shopping Center have the best selection of designer brands: Chanel, Dior, Louis Vuitton; Valentino, Louboutin, and so forth.
The three things you must see are the Casino Square, the Prince’s Palace, and the harbour. Play in the casino, take a walk, and explore Monaco-Ville — Monaco old town — and have a drink at Café de Paris. If time allows, plan a day trip to Saint-Paul de Vence, one of the oldest and most beautiful medieval towns on the French Riviera — the scenery is breathtaking. Another worthwhile venture is to break out of “tourist mode” and visit the Condamine area, where you can interact with ordinary people from Monaco.