So I'm looking for something that can allow my party to plan elaborate heists/assaults/rescues, a la oceans eleven, or the great escape, without having to plan the place they're going up against for 3 years. I've done it with FAE and Pathfinder, and they liked it well enough, but there's gotta be something better for this. Do you know anything to help?
In terms of matching both mechanics and flavour to the purpose at hand, your best bet would probably be the Leverage RPG. It’s based on the television series of the same name, so if you’ve seen it, you know pretty much what you’re getting into. The game operates on the basis of abstract “assets” rather than precisely statted out obstacles, and there are basic mechanics for spending player currency in order to have a flashback scene and retroactively explain how of course you planned for exactly this eventuality, so it takes a fair amount of weight off of both the players and the GM in terms of setup.
If you’re interested in an example of a game that takes the same approach much, much further, you could also have a look at Blades in the Dark which carries the planning-via-flashback conceit to its logical-yet-faintly-absurd conclusion by allowing nearly everything to be declared retroactively.
For example, when you’re gearing up for a heist, you don’t pick out equipment at all; you just declare how heavy your load is, and based on that decision, you’re allocated a number of boxes you can check off to declare “hey, I just happen to be carrying the exact thing we need for that”. Even the basic action resolution mechanics explicitly don’t distinguish between actions taken in the present and actions taken in the past, so - for example - when encountering a guard in the middle of a job, you can declare that you’re making a diplomacy roll for your attempt to bribe him last week, even though the guard’s existence in the game wasn’t established until that exact moment.
The reason I didn’t recommend Blades first is that tonally, it’s extremely, extremely wrong for Ocean’s Eleven. “Gritty” doesn’t begin to describe it - the default premise is that you’re a gang of cutthroat petty thugs in a haunted city of perpetual night whose rulers may or may not all be possessed by demons. So, y’know, it’s missing a certain joie de vivre. I’m not saying it couldn’t be made to work, but you’d have your work cut out for you!