I have been loving appliqueing with leather lately. Especially for dots...it doesn't fray! However, I'm doing a huge leather piece right now and the blanket stitches were looking wonky and it wasn't traveling under the presser foot right. The stitches were way too close together and as needles leave holes in leather ripping really isn't an option.
What to do? My mom to the rescue! This is a Bernina 56 foot. Why is it green? It's Teflon coated so it glides over the fabric! It worked like a charm and my blanket stitches looked MUCH better.
You have to be careful when appliqueing leather because the layers can start to separate as shown right in front of the needle in the picture below. What to do? Make sure you use a large width. I usually do 2.0. With leather, I go at least 2.5 for width.
I hope you get to quilt today!