Hi and welcome, from Oklahoma.

I like Staem-a-seam2 but some here say it gums up the needle. Mine never did.

I use wonder under by Pellon all the time and I stitch around it with out a problem. It does NOT gum up my needle and most of the time I use a satin stitch. Have been doing it for as long as I can remember. Steam a Seam is nice but more expensive to use

Hello and Welcome :D:D:D

I use wonder under all of the time, but I like the finished look of going around the edges with a blanket stitch.
I would question whether the edges would unravel after a few washings, no matter what brand that you use :D:D:D

If you are going to sew around the silouhettes, I would do it while they are still blocks...it is much easier than trying to do it when the top is put together :wink: The more you handle them, the greater risk of them starting to unravel, too.

Hello and welcome from SW Iowa. I would use wonder under.