Oh, yeah, that was one of my favorites. I loved Bee Mario, too, I actually have him as a plush. =P But yeah, I liked Ice Mario, but Spring Mario was a pain. >_
I did the same, but then I started getting all the stars. Need to beat the boss again. My favorite out of all the types of levels is the Purple Coins, those were always fun. =]
From what I heard, Yoshi will be in it, but that's about it. Though I hope the music will be as awesome as it was last game, that was the part I liked the most. =D