I thought iMovie 06 and below were really intuitive and easy and powerful, I just don't "get" iMovie 08. Honestly, I haven't used it much because I find it intimidating, and I can't figure out how to do basic things like the selecting the placement of an audio track. At the same time, people have said that it is easier but less powerful, so maybe in an attempt to make it easier it just looks harder to people who are used to the older versions.
I think iWeb should be more useful. I'd love an app for the Mac that has the functionality of like Adobe GoLive 4. I "got" that app. I've dabbled with DreamWeaver, and it's too much for me. And iWeb is too little.
Never touch GarageBand or iDVD.
For iTunes, umm, this isn't too relevant to iLife, but give us more iTunes plus music and HD movie rentals, and HD TV season rentals. I just mention that since I can't think of any new software features for iTunes.