I wanted to tell you about the picks I use for playing guitar and some bass. I use 4.0mm to 4.5mm traditional shaped stone guitar picks. You may think that using such material on guitar strings would be thin sounding. They are anything but... Because of the polished surface the picks do not hang or catch on the strings while playing. They make picking much easier than with a traditional plastic type pick.
There are many thicknesses but for me I like them really thick. Here are a couple links to check them out.
Tell them I sent you...