Interesting thing from the Exhibition Arena that I'll freely mention since both sides are doing it.
Many creatures have extensive SLA buffs at-will, or with multiple-minute durations. It occurs to me that if a GM presents such a creature in a prepared state, there are a lot of things to layer on the stat block. One of which that was not obvious to me was that if you have an ability that will last for 10 minutes, and you can cast it at will, then you might as well throw on a couple layers of it incase of dispel. I envision a platoon of teleport-capable demons, for instance, about to launch off and attack heroes who threaten their infernal aims. They easily have 5 minutes to prep before their boss gives the word to "JUMP" - that's 50 spells, many of whom will last 5 minutes post-Jump even if cast first, longer than any expected D&D combat.
It would be a real service to GMs if fully-loaded "5 minute prep" stat blocks were available for such creatures, which perhaps represent at least a quarter of all those over CR10. It seems to be even more critical the higher you go in CR. I wonder if any publisher out there has looked into that, or if people would actually pay smallbucks for such as a download.
On a related note, I think that this might emphasis some creatures that are popularly considered "under-CR" such as planetars with their 17th lvl cleric abilities at CR16. The general counter-argument is that abilities which are powerful for PCs aren't as powerful for NPCs since they only exist in-story for a few rounds. Depth of power isn't important if you only live long enough to cast 4 spells - who cares if you have 20 more spells in your arsenal. Similarly, if a PC could convince their GM to get them "cure minor wounds at will", they'd suddenly be able to heal the entire party between encounters (for many values of level).
anyway, rambling done... thoughts?