Thread choice for small goods

[photoguy13]

I was curious to see what you thread size you are using to sew card holders, wallets, etc.. I have been hand stitching but purchased a sewing machine to speed things up with more goods available, etc.. I am typically sewing leather together that totals anywhere from 4 to 11oz.  I am thinking I would begin with 138 with a fairly tight stitch at 5mm.  I think it looks nicer.  Do you think 90 thread would look cheap and thin.  I am using nice Horween seconds, etc..  What is your go to thread size when sewing nice small leather goods?

[Roq]

I use 138 for most smalls