I also went almost four years ago when I went to Dublin for New Year. And I saw the museum back when it was larger and the entrance was on Merrion - is that right? It was beautiful then. And totally agree about The Taking of Christ. It's fabulous, and really the overall quality of paintings there is fantastic.
I didn't get to see the Leech, but I looked it up, and I now regret paying less attention to the Irish paintings when I did my walk through.
During my stay most recent visit, I stayed at Merrion Hotel, which has a pretty incredible collection of art, too!
The Kunst Museum in Vienna is absolutely incredible. I think that the massive Klimt they have up won't be accessible after a few more weeks (here's a photo I took of a part of it: http://instagram.com/p/QZ-Ty-zOk2/
), but the paintings they've got there are just ridiculous. Carravagio, Titian, Bruegel, Rubens (another of my favorites)...And next year that wing with the Hapsburg trinkets is going to mind-bogglingly amazing.