If you want to collect the milkweed seeds, you must leave the pods on the plant until they turn brown and dry. Some people put fabric over the seed pods so they won't loose seeds, if the pods pop open, before they get back to harvest them. Also you can put a rubber band on the pod to keep it closed. Once you collect the pods, it's ok to cut the plants down. I've found with common milkweed, that if it starts growing in an area, where I don't want it, I can just keep removing the above ground stalks and the plant will get the hint, and move elsewhere. That's pretty low maintenance. Good luck with your milkweeds and native garden!

Do not bother them! There are very highly likely caterpillar eggs still on them. The milkweed can handle being eaten to the ground and will come back next year. Leave the plant as is, keep watching for generations of caterpillars and the time from from egg to chrysalis is about a month, and egg to butterfly about six weeks (if my memory is correct). You still have at least one more generation of butterflies that could hatch. If you want to harvest the seeds, follow Jay's advice.

Be aware the common milkweed, Asclepias syriaca, spreads vigorously by underground rhizomes. Other varieties do not necessarily. My swamp milkweed, Aslcepias incarnata, does NOT spread via rhizomes. Well behaved with all garden neighbors. Do a search to find which type you have.

It’s wonderful to hear of your experiences growing native plants and how you’ve involved your children. I agree with Deanna about determining which type of milkweed you have. Swamp Milkweed is a wonderful plant to have in your garden. Very well behaved. It does seed out, but this has allowed me to create a nice patch and to share plants with friends. (The common variety is a much more invasive plant.)
Native plants are a wonderful addition to the garden. Once established, they are very, very hardy and maintenance free. There is an enormous difference in the number of insects that are attracted to them compared to the other garden plants - bees and butterflies. I live in zone 3 but I’m sure many of the same plants would do well in Michigan. In addition to Swamp Milkweed, these are my favourites: Joe Pye Weed, Giant Hyssop, Culver’s Root, Prairie Crocus, Three Flowered Avens and native Monarda.
I leave the spent flowers and seed heads on my plants over the winter. I have been surprised by the number of birds that are attracted to these during the winter. Even now, American Goldfinches are feeding on the seeds of my Giant Hyssop. What a wonderful sight in the garden!

Each pod will contain many seeds. How many pods do you have? If you will not need very many seeds, then cut off some pods, in the interest of leaf growth (winter is not yet).

The plants tip to the ground only if you let them do it; so....

I have 6.5' tall plants that continue to make nice leaves. I cut short the tall plants that had quit making nice leaves.

One argument for not cutting the milkweed stalks down is that you will need them in the spring to remember just where they are, as they come up so much later than most perennials (so does Culver's Root).