Brahms did have a golden autumn. The late piano works are on a par with late Beethoven's, though Brahms tended to avoid larger multi-movement structures and there are no amazing late sonatas or sets of variations like the Diabelli. The clarinet quintet is a treasure. I don't go for his big orchestral works much, feeling that he was too much under Beethoven's shadow and that the strain of that shows through in places. I love the fourth symphony, though the other three leave me cold. The Variations on the St Anthony Chorale are also very uplifting. None of his concertos do it for me at all. One of my very favourite Brahms pieces is the set of piano variations on a theme by Handel. Such life-affirming drive! As you say, he wrote beautifully for the voice. I have to admit to a severe language barrier when it comes to lieder!

Having said all that, if Brahms comes on the wireless I'll not turn it off, ever!