Red Rock Threads is my go-to website for all things thread.
I travel enough that I am able to visit lots of different stores so am generally able to find what I need in a store, however when I'm stationary or need something special Red Rock has it.
For hand quilting they have
40 wt Floriani, Gutterman, Signature, King Tut by Superior
50 wt Robinson-Anton

edit to add that I've done a bit of hand quilting with King Tut variegated thread, and just hand waxed it first.
Do you run your hand sewing thread through one of the wax discs, then iron the wax into the thread? I thread up 5 or 6 needles at a time and wax & iron them all at once.

Here is a link that might be useful: Red_Rock_Threads_quilting_thread

This post was edited by mlweaving_Marji on Wed, Apr 9, 14 at 10:13

Forgot, they also have the YLI 40 wt hand quilting thread, huge variety of colors
"aYLI 40wt 3-ply Hand Quilting Thread has a glazed finish that is perfect for quilting by hand. The exclusive glazed finish means YLI Quilting Thread will pull through materials with ease, making YLI Quilting Thread the thread of choice for serious hand quilting projects."

Here is a link that might be useful: YLI-Hand_quilting

There are a lot of thread choices, but still not many color choices for hand quilting thread.
Was hoping to find a light grey solid or variegated.

Joann's sells hand quilting thread online. Below is a link for a variegated light grey hand quilting thread. I prefer and have used for many years, Coats & Clark Hand Quilting thread. I hand quilt all my quilts.

Best to you,
Sandra

Here is a link that might be useful: Joann's

This post was edited by quiltingfox on Wed, Apr 9, 14 at 14:40

The Joann's near me has many different colors and brands of it. I haven't bought any in a long time, but the one I used to get there, Americana, is very good, many colors and is cheap cheap cheap.

Thanks for the great info. I'm in Canada, but can order from Joann's. I usually go to Bangor a couple times a year, so will be sure to stock up next time.

Did you look at the red rock threads page? Just between YLI and Gutterman there are 83 hand quilting thread colors. You have to scroll through.
There are several greys