I haven't downsized - most of the time our 5 br, 3 1/2 ba house holds just the 2 of us. I think about it. Especially since my house has seldom-used formal LR and formal DR.
But. Both our kids moved away but within driving distance. Four or five times a year the house is full and happy with kids and grands. For now, that is worth it.
When we downsized my in-laws years ago, DD was moving into her first apartment so she got some furniture. DS was in college and got plates, pots, pans. BIL and DH took what they wanted and we either donated or trashed the rest. The hardest was an old player piano. We tried so hard to give it away, even called the manufacturer. But in the end, 1-800-Got Junk came and threw it in the back of a truck.