Potassium ferricyanide will probably work best. This is the traditional reagent used for laboratory demos, with a strong hydroxide base and peroxide of course. If you can find some, I would recommend it. As I said, many well equipped chemistry labs will have it in stock.
If you can't find ferricyanide salt, then you can try the copper salt as a substitute. It SHOULD still work, but I don't know if it will work as well. I'm not sure how well copper catalyzes the reaction compared to iron. But, it can't hurt to try.
You basically want to ensure you're using the same number of moles of your copper as you are of your iron. So you'll need to find out how many moles of potassium ferricyanide the recipe is asking you to use, then find out how many grams of copper sulfate hydrate you need to substitute to give you the same number of moles of copper.
If you heat it up, the reaction should be more intense but not last as long. However if you're not going to be doing this in a hood, I would suggest you do not heat an open system of strong base and peroxide on a bench. If you need to show the effect of temperature, consider having a second one that you cool down - it should dim and last longer, the same way you can preserve halloween glowsticks by sticking them in the freezer.