I made a couple Rainbow tunics for the Birthday Girl, with Saila modelling one here:
This is from the Ready for Spring Top and Tunic for 18 Inch American Girl Dolls pattern on Ravelry. I really enjoyed this one as it was simple, and very well written. I'm often knitting in ten-minute-bursts before the next interruption, so something that I can pick up and know where I am immediately is a boon.
The other thing I really enjoyed about these was the yarn! I've admired the Knitpicks Chroma for some time, but it's more expensive than my usual yarn. So it was lovely to have an excuse to buy it! I just love the gradual colour changes - there's no worrying about switching yarns, or weaving in 400 yarn ends when you finish, just smooth, cheerful colour.
Once the birthday presents are done, I will definitely be making Saila one of these to keep. :)
Here's what it looks like on a Journey Girl:
A little looser, but still good! I also found that the pants I got the other day from Etsy fit the Journey Girls really, really well, much to my surprise. :D