When I can't think of how to scrap a certain picture or set of pictures, I just put them aside and glance at them whenever I'm perusing my pictures for the next layout. Sooner or later, I get an idea and it almost always works out great and ends up being a favorite layout.
The times that I've forced myself to scrap a group of pictures because I felt like they needed to be done now-- I've always hated the resulting layouts. I have one layout that every time I see it, I cringe. That one is going to have to be redone someday-- I'm just waiting for the inspiration on how it should be done properly.