Nope, nothing in Monaco.

But with that said, definitely check out all the hotel cocktail bars - great people watching, drinks and snacks, architecture, etc. Hotel de Paris (has live music) and Hotel Metropole are the best. The Casino too, to see it and for the experience.

Hermitage is ok (great building, but bar not as interesting or fun). Fairmont has great views from rooftop pool and restaurant, but is more of a convention hotel.

In the harbor on Quai Albert 1er, there are a couple of bars/restaurants where people are outside for happy hour and into the evening, crowds are eclectic and mixed - and is much more casual than the hotels by the casino.