Okay, so I've recommended pinafore.social as an alternative UI for Mastodon on the web, and then elk.zone (which is in alpha, but very clean), but also someone recommended Soapbox and... i think that might be my new favorite. UPDATE: people have highlighted the creator of Soapbox has some horrifying views & people may associate you with those views for using it... So... be aware. I'm continuing my search...

Still wish one of these clean interface options would implement multi-column though...