I have spent some time with the works you are describing and my most recent memory was of The Birth of Venus, Botticelli
, i spent about an hour just sitting in the Uffizi with this painting infront of my vision alone but for the idle wanderer and found my vision but did not find myself as far as i had hoped. We put the responsibility on the artist more than we do on our own situation, if you are not sitting comfortably then you will find it difficult to discover. There is also the point to be made that the works aren't as transcending as is offered by their mythology because one needs to be able to be lifted as well as to rise, i do not think i rose to the occasion, but the occasion was still pretty important and life altering but just might not have had anything to do with the paintings.
Others i love
Fra Filippo Lippi - The complete works
Fra Angelico - Olga's Gallery
Museums should play music to their audience. This would help in sittuating someone the souls experience is often through senses, music is a catalist that works me does not just make me work. I dont care if the music doesn't fit, like the works themselves it is all atmosphere.