Coats & Clark sell the heavy-duty classic orange jeans thread. I do use that with a topstitch needle when hemming, and it really is quite strong.

But for just regular garment construction, there will only very rarely more than a double thickness of fabric, so any good sewing thread will work just fine. I like Gutermann myself. I find Coats and Clark to be very "linty".

When I made jeans out of faded denim, I liked the look of a tan for the topstitching--the same found in ready-made. I used two regular weight threads on top, run separately through the tension discs, or whatever they're called, and threaded through a heavy weight (#16?) needle. The threading is the same used for a double needle. The machine's manual would describe how to do that if it's set up to do so. You get the look of the heavy weight thread but can use any color. For the construction seams, regular weight is fine. Come to think of it, I used a double thread for topstitching on just about anything--it shows up better.

Sharon C.