If you want an honest answer, probably 1950-1960, when Disney had not settled in to any particular formula and was just making whatever, typically period adventure films and literary adaptations.
During this time Disney produced the likes of Treasure Island, Robin Hood, 20,000 Leagues, Old Yeller, Swiss Family Robinson, Pollyanna, Johnny Tremain, The Great Locomotive Chase, Darby 'O Gill and others. The approach to live action was the same as animation; take well known public domain stories and reinterpret them for a modern family audience with high production values. Many of these films were made in England with frozen funds, or to save money, but they pulled from great talent to produce these titles. It was during this time all the True Life Adventure films were also released, including the unusual "Ture Life Fantasy" of Perri.
The gy Dog put an end to most of this. It was the only Disney movie to turn a profit in 1959 and made huge margins because of its low production costs. It ushered in a wave of middling slapstick comedies that made up the bulk of Disney's output (and profits) for the next decade. Son of Flubber is nothing to write home about, but it probably paid for the Tiki Room. At least some like the first Love Bug and The Parent Trap were good, but it was not a continuous period of excellence in quality. We all probably have sentimental favorites from this time though
The most experimental period of Disney's live-action output was in the early 80s leading up to the creation of Touchstone, where Disney tried to push the kinds of movies it could release under its brand...with very mixed results. It's a fascinating period that deserves more examination beyond TRON, but I wouldn't call it a "golden age".