Millennium is a great ship. We sailed her in March of 2005 with a balcony suite.
The assitant cruise director, Haroon, (sp.) was very outgoing and lots of fun. Dance classes with one of the Celebrity dancers was a blast and the sail-away parties are some of the best.
I have not had butler service yet but I believe you are in for a treat. From the complimentary champagne on embarkation to the shows, to the great meals in the dining room to the mineral pool it is all top notch and the service is excellent.
Have a great cruise and come back and tell us about it!