I literally just cast off the second bootie and sewed it up in the last hour. I am super happy with how this project worked out.
I used the Eco Baby Booties pattern, as I mentioned before, and some blue Bernat Handicrafter cotton. It was one of the tiny skeins (the one dishcloth size) and I still have about 4 or 5 yards left. I'll probably use that as trim on another pair.
I knit the pattern as indicated, but went to 4.25mm needles, because I didn't have the correct size.
I will definitely be making more of these, and probably tweaking the pattern to make larger sizes (this one says 0-6 months, but I'd love to do some up to 12 months)
Overall, I'd say these are a great project for someone like me who wants to get out of the habit of knitting rectangles, or a beginner who is looking for a small challenge.