Monaco is small enough that location differences are measured in minutes, so the question is which address suits the trip. Monte-Carlo puts the casino square, the harbour and the shops on foot: the Hermitage, the Hôtel de Paris, the Métropole and the Fairmont. Larvotto, the beach end of Avenue Princesse Grace, is for pools, sea and a calmer pace, at Monte-Carlo Bay or Le Méridien Beach Plaza, the only hotel in the principality with its own beach. Fontvieille, on the far side of the Rock, is where the sensible money goes, and the Columbus is why. Three of the ten sit just outside the borders, in France, because the best views and the only real hideaways on this coast are beyond them: Monte-Carlo Beach and The Maybourne Riviera at Roquebrune-Cap-Martin, sea level and clifftop, and Cap Estel at Èze-Bord-de-Mer.
You fly into Nice Côte d'Azur, 30 to 45 minutes by road depending on which of the ten you booked. Bus 80, the Nice Airport Xpress, runs from both terminals without a change, but the better route is tram line 2 into Nice in under half an hour for 1.70 euros, then the coastal train to Monaco-Monte-Carlo in about 23 minutes, calling at Beaulieu-sur-Mer, Èze-sur-Mer and Cap d'Ail. Monacair flies it in seven minutes from 195 euros a head. Do not hire a car. Six CAM bus lines cover the principality at 1.50 euros by card, the boat bus crosses the harbour on the same ticket, and 79 public lifts, 35 escalators and 8 travelators do the climbing for you. Hotel parking is 55 euros a day at the Hermitage and 70 at the Hôtel de Paris.
July and August are the warm, expensive months, highs around 26 degrees and the sea at its best in August. April to June and September into October are better. Three fixtures move prices hard: the Rolex Monte-Carlo Masters in early April, the Grand Prix, which has moved from late May into early June, and the Yacht Show from 23 to 26 September. Winter is mild and much cheaper, but Monte-Carlo Beach and Cap Estel are both closed.
Two nights covers Monaco and three is the number to book, giving the third to the coast. The train you arrived on is the day trip: Èze-sur-Mer for the climb to the village, Beaulieu-sur-Mer and Saint-Jean-Cap-Ferrat for the Villa Ephrussi and a flat seafront walk, Nice in twenty-three minutes. If you want the hideaway version rather than the harbour version, invert it and sleep outside the border.
The honest truth about cost: an entry room at one of the grand hotels starts around 400 euros a night in winter and can pass 1,000 in summer, and Grand Prix week multiplies everything and imposes minimum stays. Monaco is a building site in places, loud with traffic for somewhere this small, and the 400 metres your map promises is often 400 metres and sixty metres of height. It is orderly and vertical rather than charming, and if you want old stone and silence you should sleep outside it. Outside those dates Monaco is more bookable than its reputation suggests, and safe, walkable and under an hour from Nice airport by road.