"Modern Guilt" is probably Beck's most underrated album and arguably the last essential album he released. Some great songwriting on that one and probably the best production work Danger Mouse ever did. All his 90's stuff is worth hearing IMO except for debut "Golden Feelings" but given your tolerance for experimental lo-fi stuff, you might dig that one more than most (but "Stereopathetic Soulmanure" is similarly lo-fi an experimental and far more entertaining).
Oh yeah The Beach Boys' Xmas album is definitely worth mentioning. One of the few Xmas albums I always listen to during the holidays along with Ellington's "Nutcracker Suite", Ella Fitzgerald's Xmas album and "Charlie Brown Xmas".
Nice callout for the folky stuff on "Beatles For Sale"- always had a soft spot for "I'll Follow The Sun", one of my favorite early Paul numbers. And "Baby's In Black" never gets enough love- killer harmonies on that one.