lenny 1,
The only boat I'd consider for just two people would be "Breathless"..........but you'd be lucky to get a booking, and it's certainly pricey...with tax and a tip you won't get much change from $220.
Having done the Illuminations Cruise a couple of times...most of the fun comes from sharing, and you'd look totally lost with only two people on board!!!.........plus the captain's Disney quiz wouldn't be too much fun for just two of you !
You can certainly take champagne on board ( we had a New Yorker on our last trip who brought two bottles ).........but you'd probably need to arrange it yourself.
Just remember to follow the advice and ring early!!!!
mike 230652