So we have a thread for characters you want in Smash Bros. 4, but it's always been my thought that the stages are just as important (maybe even MORE important?) than the roster of characters.
Plus, a recent play-through of the N64 original (not to mention combing through the Smash Bros. Wiki) has reignited my love of a couple past stages that I'd LOVE to see return, mainly the original SMB 1 Mushroom Kingdom from Smash 64, and Brinstar Depths from Melee. If we see Past Stages in Smash 4, those are FOR SURE at the top of my want list.
As for new stuff, I've always wanted to see a stage based on the Mother Brain boss fight from the end of Metroid and Super Metroid. Pools of acid, laser blasters, destructible Zebetite barriers and most importantly, a big, destructible Mother Brain! In general I'd like to see more destructible environments in Smash 4.
So what do you want? Any old school stages you'd love to see return? What are some new concepts for stages you'd like to see explored?