Is there a way to set up custom layouts? Eg, I'd love to have a variant of tall/wide-tall that puts the main area on the right side of the display, rather than the left.
Not yet. I've toyed with different ways of doing this, but haven't really decided on one that I really like. Maybe I should just go the road of other window managers that expose a scripting interface. Write a javascript file or something that defines a function that takes a list of windows and some other parameters and returns frames for the windows, binds to commands for modifying layout state, etc.
Yeah, there's already an issue to track that (https://github.com/ianyh/Amethyst/issues/129), but in general it seems like people want more flexibility in defining how they want things to tile.
+1 for this question. I've got a dual head box hooked up to my machine, and I'd do just about anything for a window management solution that would let me divide up this 3840x1080 "virtual" display into two equal displays. Mostly so dialogs stop appearing in the split between displays.