Depending on your definition, I think there are several change-of-party elections that could qualify as landslides: Harding 1920, FDR 1932, Ike 1952, and Reagan 1980 among them. Tellingly, though, the last such was 44 years ago. (Obama 2008 is probably the closest we've come to that since then, and at least historically that wasn't really a landslide.)