I am very, very jealous. Havent done this myself but apparently if you fly into Nice, you can arrange a helicopter transfer to Monte Carlo- its not too expensive- and what a treat! Saw it on the tele one time- it was quoted at around 100 euro but that was at least a year ago. If you do this, could you please post back about how much it was and whether it was good?
There are boat tours operating all the time in the harbour of Monte Carlo which are lovely. A short drive away is Roque Brune Cap Martin ( spelling of this could be dodgy) which has a lovely old village, castle etc to explore- but lots of steps. And beyond that again is Menton, which has a lovely market to wander through, and a beach all along the sea front with restaurants all along it- very inexpensive- mmmm just thinking about a big bowl of Moules Frites and a bottle of wine on the sea front. Also in Menton there are lots of shops in the cobbled streets to explore, with little cafes in the squares and obviously much more affordable than the Hermes, Prada, Dior that you'll find in Monte Carlo. I absolutely loved the area, and am planning to go back asap.