I like the mini-gallery idea a lot. I'd really rather have a set of canned features (ie add a row of 3 picks, add an intro image, etc) than leave people to figure out how to resize and align things ad hoc-y all over the place.

I'm still looking at other WYSIWYG image insterters, but they all seem to have their flaws. I may switch tactics and just come up with a toolbox of image options, would that work for you?