Actually Nassau means 1 hr. bus rides to get to the boat ride...
We stayed in the Piscadera Bay area, there's diving offshore, about 3-4 hotels and condos behind them. The Marriott, Hilton and one other are waterfront. Good local beach bar/diveop there called Hooks Hut and there's diving offshore. It's about 15mins. to downtown and 20mins. to some really good dives to the west. It's the resort area on the west end of town - 15 mins. to the airport.
Or look at Lions Dive or Breezes, they're farther east but more in town. The Dive Bus is right next to Breezes if you want to do escorted shore dives from there - although most Curacao shore dives (we did 15) were easy walk-ins off the beach/dock. Both LD/Breezes share the Ocean Encounters boats so might be a little more crowded - we did one dive with them but canceled a second since their boat was full - instead we drove 10mins. east and had Tugboat to ourselves late morning - except for the snorkelers. There's also the other Kura Hulanda Hotel nearby - not exactly sure where.