There's more than one old hippie on this site.
True, Louis. You're in good(?) company, Spence.
Here are some thoughts about simple, versatile ties for Iso spinners and duns:
Consider tying a synthetic Comparadun style for both. In my experience, a synthetic Comparadun wing can often suggest upright-winged and spent-winged spinners (as well as duns) with good success. Additional advantages are that the upright portion of the wing makes the fly very easy to see on the water and it is very durable.
I use a dark gray or slate-colored synthetic for the dun wings and a very light material for suggesting the spinner wings. I usually mix a little tan or light gray with white for the spinners. (If you want, you can also add a bit of pearl Krystal Flash to the wing, further enhancing the visibility.) I especially like Hi-Vis for synthetic wings on larger dries, but Antron or Z-lon (or probably many of the similar synthetics) can also work well.
If you just don't like synthetics, you could achieve a very similar result by closely "palmering" a hackle (of the appropriate color) through the thorax and trimming it flush across the bottom. In either case, should you feel that you really need a spent imitation, you can trim out the center (upright) portion of the wing onstream.
Another option would be to just tie the synthetic spinner patterns and carry a dark gray marking pen to color the wing if you encounter duns on the water. (Just keep in mind that on streams with a good Iso population, fishing the dun imitation as a "searching" dry can often work surprisingly well even when you don't see duns on the water.)