Nice or Monaco

They both have things to see and do but I'd stay in Nice which probably has more choices of accommodation. You could do a day trip to Monaco. There are lots of smaller towns to visit too from Nice (via bus or train) like Antibes, Cannes, Grasse, St. Paul de Vence, Eze, Menton, Villefranche, Roquebrune-Cap-Martin, etc.

Nice, absolutely! you could still day trip into Monaco.

Absolutely Nice. Monaco is rather dull (IMO), although Eze, which is on the way, is lovely.

Nice as there is much to see and do. Day trip to Monaco.

I most definitely agree with the others - Nice! You can easily take a day trip to Monaco or any of other towns in that area.

Thank you all. Decision made; Nice it is. Any recommendations for hotels?

I liked Hotel le Royal in Nice.