While it's tough for me to talk about any Beatles tune like it's a hidden gem, Your Mother Should Know is perhaps one of their lesser known successes that I always get a kick out of. I love the weight and jaunty tone of this track in particular. It remains upbeat but restrained from the rambunctious style that highlights so many other Beatles hits.
The Magical Mystery Tour is one of my favorite albums of all time! But look at the tracks listed on the cover art - they could all be considered inspired singles for numerous reasons.