Honestly, I'd be content if LDD had even a small, basic play around mode like LC1 did.
I can get my fix of building random things in Digital Designer, seeing as it's essentially an improved Creator build mode with nearly all bricks, but I really miss the charm of watching those creations run around and do things.
While I'd welcome a Creator 2, I like LDD's build mode so much, I kind of wish it would just be an add-on to that, even if it was just the basic features ported over from creator, such as moving minifigures and Drivable/Flyable vehicles. While I'd be more than happy with just that, part of me would really like to see a full-blown sequel that takes advantage of what is possible to do now. More detailed environments of a larger variety, weather, boats, spaceships and other misc. vehicles... It'd be great fun.