I went last year for the first time and it was amazing!!! So i'm going back again this year, i'd look at getting your ferry asap, last time i looked when i booked most of the popular days to sail had sold out.
Definitly worth a watch from Ginger Hall, Bungalow on Mountain, Creg ne bar and sulby straight. And as Skin says definitly Bray Hill!
Mad Sunday is worth going out for but expect the mountain to be opening and closing all day, we went out early most mornings and some mornings you wouln't see another bike on the mountain but as the day gets on it gets busy and accidents close it for short periods.
It is ace tho, i can't wait and am counting down the days till i'm on that ferry!!