My husband and I sailed on the Celebrity Millennium for a 5 night Western Caribbean cruise. This was our second cruise (sailed on Celebrity Solstice to Eastern Caribbean on a 7 night cruise in May 2010 with our college age kids and my parents). It was interesting to sail on the smaller M class ship and to see what a shorter cruise was like. We had a great time. Having sailed on the Solstice, it was easier to find our way around the Millennium - theater forward, dining rooms aft, etc.
We flew into Miami 2 days before the cruise so we could enjoy a stay on South Beach. We stayed at the Park Central Hotel on Ocean Drive - right in the heart of the art deco district. The location was great. The hotel is a nice art deco hotel. It was rated well in Trip Advisor and the price was great for a clean, comfortable hotel in a great location with nice amenities (complimentary beach chairs, pool, roof top lounge). We paid $140/night which seemed to be reasonable for the area. Unfortunately it was rainy, and we didn't get to enjoy the beach, the pool, etc. It was very easy to get a cab for the short ride to the Port of Miami.
We arrived at the port shortly after 11 a.m. The embarkation process was quite efficient. There was a bit of a line (maybe 10 minutes or so) to actually get into the ship. We enjoyed our glass of champagne (a nice touch which apparently is not always done). We talked to some of the ship representatives about shore excursions, beverage packages, etc. We made our way up to the buffet in the Ocean Cafe for lunch. Lunch was very good, and we had a nice table with a view towards Key Biscayne. After lunch we explored the ship while waiting to go to our cabin.
Nice cabin. Aft location - very little traffic down our hall. Quiet. Room was nice. Balcony was nice with an unobstructed view.