On a 747 upper deck there is an exit (in LY case - between row 74 and 77). The area behind row 74 is usualy open and can be used for storage of small bags. If you look at this picture, you can see the 2 boxes marked as S in the map. They are 2 small closets or other storage ares behind row 74 and in front of the exit door.

In general, the upper deck is more recommended than the lower deck because it more quiet and much smaller (4 in a row compared to 7 in the main deck). The main deck cabin is also very close to the coach cabin.
The overhead bins in the upper deck are very small (comparable to regional jet bin size) but there are additional large bins between the window seats and the wall/window.