They picked us up about 45 mins before Wishes, so total it was about an hour or so. It was pretty pricey, especially on top of vacation cost, but you can have up to 10 adults, or if it's a mix of adults and children I think they take up to 12. I think it was $275.00. You can also book the same type of cruise to see Illuminations at Epcot, but of course not as convenient if staying at the Campground as the one for Wishes.
They also decorate the boat with balloons and a birthday banner. If you REALLY want to go all-out you can order a birthday cake and have it delivered onto the boat prior to leaving. There is a whole section on these boards about birthday cakes as they have taken on a life of their own! LOL I didn't do the cake - he was much happier with a "beverage"
The birthday button is definitely a "must" - even if she thinks she will be embarrassed.

I can't tell you how many people will wish her a happy birthday, not just castmembers.

Plus, you just never know when the pixie dust will be sprinkled.
You can also look at allears.net, they have a whole section on things to do to celebrate birthdays.