One major gripe that I have about WHM is the long cast times and lack of instant abilities. I find myself stacking spell speed every chance I get in a desperate attempt to make myself more mobile. I try to save regen for movement and I also try to save my utility abilities for movement. but regen lasts so long, you're not casting it very often. I am a farily conservative healer and I tend to always save swiftcast for raising people and likewise benediction in the event that the tank drops to 10% or less.

Demon wall in AK is a great example of where I wish I had more instants - mainly for the final phase when adds spawn. I can certainly keep regen on everyone then, but some dps still require more healing than that and it is quit tricky avoid purple, red circles, dispelling, and finding time for a full Cure to cast.