Hello Maggie,
welcome to the board!
I am using solid fabrics a lot because I do wholecloths. I tried the Kona cottons once and I must agree, it was quite hard to sew them by hand. As far as I know the Konas have a thread count of 60/60 - like many quilting fabrics! - but I think they are quite coarse.
You could try the Moda Bella Solids. For me they were easier to sew and to quilt compared to the Konas. My favourites are P&B, but they seem to be disappeard from the German market. One of my LQS offers solids by RJR but I haven't tested them yet.