Unless I forgot a coin or two, I believe I've presented a "Design Discussions" index post about all of the coins of the classic US commemorative coin series: 50 for the silver types, one for the Norse-American medals, six for the gold coin programs (some of these posts cover more than one type coin) and one for the US-Philippines Commonwealth coins. (A complete listing of the posts can be accessed via Commems Collection
by clicking on "Design Discussions" at the top of the CC page.)
Before I leave the "Design Discussions" series, I just wanted to reiterate that these index posts were meant to supplement my history-focused posts about the coins that can be found via the Commems Collection
list. There's much to learn about each of the classic-era coins, and history and design discussions go hand-in-hand. Hopefully, the various indices presented will make it easier for you to learn about multiple aspects of a coin of particular interest.
Previously, I put together a series of topical index posts to offer folks a theme-based approach to collecting a subset of US commemorative coins. You can check out these indices via Commems Collection