Agree about Dubai or Oman.

Muscat is a great place to visit, but it is a sleepy spot with of the same activities (water sports, laying around) as you'll be doing in the Maldives, and minimal good food or nightlife. It does have a nice city center and bazaar (souq), as well as the rugged terrain and other culture that muscat mentions, but you might prefer a bit more action before going to the Maldives, making Dubai perhaps a better choice this time.