Nice would be a good choice. I recommend Hotel La Perouse - a four star - that is nice but at the lower end of the four start price range in the off season. Definitely suggest renting a car. Monte Carlo will be more expensive, and unless the casino is really important to your brother, I wouldn't recommend staying there.
http://www.hotel-la-perouse.com/
Another hotel has great views and is pleasant, but NOT centrally located, is
http://www.hotel-terrasses-eze.cote.azur.fr/