I strolled up to the upper deck once and was intercepted by a FA once I was there and told that security now prevented people including that deck in their walks round the plane. I was in F but that does not matter. They do not mind you strolling round the rest of the cabins.
If you get to the upper deck why not ask the occupants of 62A/K to stand up for a few minutes so you can get a good appreciation of the attractiveness of these seats. They can get up and out easily. It could start a very interesting FT thread!