To feel on the top of the world
To be on cloud nine
To be in seventh heaven
To be happy as a pig in (muck) -sh*t (muck is politer but I've never heard it used that way)
I don't really use any of these expressions but they are well known in "my" part of the world.
Tickled pink is also well known although I don't think I've heard anyone actually use it.
Not a teacher.
- For Teachers