Classical white hat parking will bring you a few buck per month per domain with residual traffic on Sedo.
Would make much more sense to create an autoblog on the site's previous topic and ideally to restore the pages using waybackmachine so the existing links remain relevant.
Or to sell that as an expired domain traffic to third parties. Just having them pareked is maybe justified if you have many hundreds and not enough time/resource to restore them all to their initial beauty - then Sedo parking is better than nothing.