A couple of animation that feel good to me are: * fading the screen around a popup or other notification that must be acknowledged. I think this serves well to

A couple of animation that feel good to me are: * fading the screen around a popup or other notification that must be acknowledged. I think this serves well to direct the attention. * moving/shooting a message out of the screen to show it's being send somewhere. Apple Mail does that as well. * Highlighting a part of a list that was changed by an action. Fading it out after a single row has been deleted for example. None of this should ever take more than about 0.5-1 seconds, with the exception of the send-notification maybe, that signals/celebrates the end of a longer task.