There are two main options for nightlife in Marbella. The first is near the city centre, the second is in Puerto Banús, so if you want to be based close to the nightlife, it should be around those places. Just as a warning though, Puerto Banús is going to be much more expensive than staying anywhere else in Marbella. Not only hotel-wise, but drinks, food, shops will also be very expensive.
Accommodation options in Marbella for nightlife
If budget is not an issue, you must stay at Villa Padierna Hotels. Michelle Obama chose this hotel for her holiday. To cash in on the publicity, the property owners christened the villa, Obama Villa!
I would suggest you opt of of a conventional hotel and instead stay in an apartment. There are many listed at Airbnb, housetrip, homeaway etc. You can choose an apartment in old town as it closer practical and also close enough to all the nightlife hubs.
As to nightlife, you can try Funky Buddha or Seven, as well as many other bars and discos with good vibes around the Plaza Antonio Banderas. As to going out in Marbella, you can try a bar with very good beer called Indian Bar and you can go to the Puerto Deportivo, where there are a few discos and bars as well, for example, a place called Lemmon.
Let me set this straight - Puerto Banus is an expensive town. It aims to be the playground for the rich and famous, so accommodation, nightclub or food, everything is expensive at Puerto Banus. So unless you are born with a silver spoon or you are already rich and famous, give Puerto Banus a miss. You can always visit Puerto Banus to see the celebrities but avoid staying at Puerto Banus.
Marbella is an upscale resort. Accommodation is going to expensive. I tend to favor staying in Malaga or any other towns in Costa Del Sol rather than staying in Marbella.
If you have decided to stay in Marbella, stay at the city center - Marbella Pueblo. It is a charming area with many apartments for rent, especially near the Orange Square.
If you want me to name one hotel for you to consider, it will be The Urban Villa Boutique Hotel. The hotel is on a hillock about 7 minutes from Marbella. Parking is free but the highlight is the panoramic views of the sea.