And TBH, I'm not entirely sure how else they could have played the wedding after all the guests saw the monsters.

Yeah, but the set-up was unnecessary. "Hi, you're infected with alien parasites, therefore you're under quarantine until we figure out what they are, if they're controlling you, and how to remove them. Have a pamphlet. The End." The guests wouldn't have seen the monsters in the first place had anyone involved shown half a brain. Their bad decisions led to the need for Retcon, and despite prior lip-service to the contrary, Gwen's good with that. Setting aside my dislike for plots that only work when people are idiots, it's bad characterization for her, because taken with her prior actions, it indicates she's okay with using Retcon to hide her own mistakes. That's amazing and daring character work when acknowledged by the text. It's problematic and creepy when the showrunner doesn't see those actions and motivations as morally ambiguous.

And what I would have loved to have seen (and occasionally flirt with writing) where Suzie lasts most of the first season and you only find out in retrospect that she's been a serial killer all along.

Have you read sam_storyteller's Season Zero? It's a meta-filled faux season set before "Everything Changes" and I think you'd like it.