I got far enough along with the bamboo to attempt to ply it. I was NOT happy with the result. Way too loose a ply. In my frustration I totally trashed the singles. I do still have plenty of fiber left, and I think that it's just a matter of finding the right project for it.
PLYING TIP: Part of what gives me hope is that I've learned something about plying since the failure with the bamboo. My friend Liz saw yarn of mine underplied, and we simply ran it through the spinning wheel again in the direction of the original ply, to ply it tighter. The resulting yarn just after plying was coiling up on itself. Now, I had worked under the assumption that the coiling indicated the ply was too tight and it wouldn't result in a balanced yarn. NOT SO! Once I washed the yarn, the coiling and kinkiness were gone - I didn't even have to weight the yarn down when drying it. So, this makes me think that I can ply the bamboo much tighter than I thought I could, and end up with a wonderful yarn.
The other thing I'm considering with the bamboo is creating a kind of boucle style yarn. With a boucle, I can spin two singles with opposite twist (one Z twist and the other S). In plying, one will get tighter and the other will fluff out, yet stay held together by the other. The bamboo would be good for the one that gets tighter.
Here is an example of a sort of boucle which I spun with silk and wool Sue H. gave me. The thin is the silk, the blue is the wool.