Well, his style would have been perfect to take over Creepshow, and there are a number of stories he could have adapted for that (in fact they did a psudo-sequel to Evil Dead on the creepshow series which featured his brother as an actor).
He specifically mentioned Night Shift, and considering his ability at creating fun but effective gross out gags, I think Graveyard Shift would make sense. But he also seems to be pretty clear that he doesn't wanna do a remake, or a story that's been adapted before. I can imagine a particularly fun and wild adaptation of Trucks/remake of Miximum Overdrive with his distinct shooting style, but it would seem to have to be influenced largely by the earlier movie for him to do it.
Battleground could be cool, but it was already a pretty cool episode of the generally not-so-good series Nightmares and Dreamscapes. Maybe The Boogeyman or I am the Doorway? They haven't been done before, and there's a lot of room for a filmmaker to interpret the tone and the plot there.
He also mentioned a Rob Reiner adaption that he would have liked to do. Obviously, there are 2, so you'd have to guess which one. I'm thinking Misery, because of it's snowy setting and isolated cabin location, both of which Sam Raimi obviously has experience with.
It's interesting to speculate because Raimi kind of has 2 different modes; the wild and fun brazen cartoonish camera work kinda thing (Evil Dead movies/Darkman/Drag Me to Hell) and the subdued serious drama (A Simple Plan/The Gift/For the Love of the Game), and of course sometimes those modes meet. But I could easily see him be drawn to doing something more along the lines of the Frank Darabont adaptations.
So in Night Shift there's also Strawberry Spring, which could use a lot of interpretation, but is essentially a cold/stark character study and serial killer mystery.
Stepping outside of Night Shift, I'd say The Jaunt is one that could be done in a lot of different ways. Maybe in The Death Room.
Or perhaps, even though it's been attempted already, maybe Sam Raimi, with his previous interest in gunslingers, is the right guy to try his hand at The Dark Tower.