Agreed, visualizing things in the editor is quite hard right now.
What I've been doing is I ad to each object an animation I call "icon". In it I draw a *really* rough sketch of how the object look in 3d. It's helpful for navigating the Events sheet and such, but it doesn't help in the Layout view.
If we had the option to use this "icon" as texture in the Layout, it wouldn't look very pretty, but we would be able to at least identify different objects.
Or even just use it as some sort of sprite placeholder in the editor? Although that might cause problems if the object is not 1x1.
Anyway, some improvement in that matter is something I'm really looking forward to.