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Will be doing portraits and low lighting at Walt Disney World in attractions...
The L might be useful here if you want maximum subject isolation. But if you want to give some sense of the context, you probably wouldn't be shooting at f/1.2 anyway. In extremely low light, the faster lens will extend the ability to AF by about 1 EV, simply because of the 1 stop advantage in aperture. Otherwise, if the 1.8 can AF at all, it will do it faster.
There are differences in bokeh, chromatic aberration, and ghosting with strong backlight, all of which could come into play at Disney World, but either lens can give you great images if used appropriately. If I were heading there, I'd probably bring the 85 L along with 35 L and a pair of zooms, but don't sweat it too much. You'll do fine with either 85.