Monaco is exciting but tiny; Are you planning on spending your entire vacation there? is this the first time you come to this area? How many days will you be there?

If you have not visited the south of France in the past, I would highly recommend traveling around a little. There are several nice threads with ideas and suggestions. do a search.

It may be easier/cheaper to stay in Nice and then do day trips. Renting a car and driving the Riviera is easy (not cheap).