Eye of Ctulu: With Ctulu...
Brain of Ctulu: ^
Skeletron: A sleazy old man and in a dungeon...
Queen bee: Either in honey, as a worker bee or as a king bee... No fun prospects.
The Destroyer of worlds: Go ahead and breath underground...
Wall of Flesh: Living in hell. With demons, imps and lots of other nasties. Also, deadly lava.
Mechanical equivelants: See pre hardmode bosses.
Plantera: Living underground, with large stingers and more poison then you need.
Golem: A mechanical solar powered thing? Isn't marriage supposed to be union of creature with creature?
Pumpkin boss: Halloween 24/7 gets boring after a while.
I can handle some cold and living on a sky island isn't so bad.