All right mate, been a while, hope you're well.
The train line, along the coast, is really good so you can jump on and off in places like Villefranche, good for seafront restaurants, Cannes, for the yachts and expensive shops, Antibes, lively and more down to earth. There's lots of Brits who work on the yachts etc. Lunch or early evening meal in the covered market is cheap and very cheerful.
To be honest the nightlife of the Riviera isn't like the UK, Spain, etc, and Nice is probably the best for you, Irish.bars and the like plus loads of good restaurants. If you like pizza go to La Pizza which is huge and always busy.
It's worth taking the short train journey to Vengtimiglia, Italy, especially on Fridays when there's a huge outdoor market, some good cheap gear, atmosphere and restaurants. Watch out for pickpockets and black lads selling fake designer gear that the police will confiscate.
Monaco night clubs are a bit tame and can be very expensive. The best reasonable cost restaurants are on the left side of the slope down from Casino Square to the port. Also the area round the harbour in Fontvieille has good traditional food for the locals who work in the shops and offices there.it's a short walk to Monaco's stadium, in fact everything is a short walk in Monaco.
If you fancy a look into the Hôtel de Paris, on Casino Square, where all the mad cars are, you'll have to get past the concierge who's no mug. Walk up and tell him you have a package to collect, from reception, from your boss, Mr Melnichenko ... he speaks a dozen languages so no bother. Walk in past the horse statue, rub its knee, and go to reception. Ask for the package, which they obviously won't have, say thanks and stroll out making sure someone is at the bottom of the steps to take your photo as the concierge opens the door and salutes you
On that note, approach one of the super smart police and ask for directions to the Hermitage Hotel. He'll salute you, which I always found funny, or arrest you if you're wearing shorts with no shirt and refuse to leave the square. I spent my one and only night in jail, in Monaco ... too long a story for here, I'll tell you next time I see you. My cell mate was a fella from Lyon who'd done just that and was locked up, taken to court and fined a thousand francs!
Hope you have a cracking time mate ...
... even in March it'll be sunny enough and busy enough