Meryaten: Thanks.

The rainbow pattern is actually the first colour choice I've been 100% satisfied with as it really works well with my general fashion style (which should tell you something).
Pearls: I guess it depends on the ortho assistant. The one I had that day was really friendly and pleasant, and actually seemed to have fun doing a more involved pattern than usual.
Maybe the orthodontist office you go to is different, but at mine, they just pluck the ligs off the little rows of plastic they come on. (They definitely don't throw away half-used ones, since they've just been in the drawer, not anyone's mouth!) And I actually had her put clear ligs on the rest of my teeth, just so that I could see what they looked like, so I used an even larger variety of ligs than pictured!
I guess what I'm saying is that it wouldn't hurt to ask. The worst they can say is no, right?