I saw the Washington Opera's Tristan & Isolde last night. Originally, Deborah Voight was to be Isolde but she withdrew a week before the run began. Apparently this was because she decided she is not right for the role. She was replaced by Iréne Theorin, who seemed to me to do quite well. I also liked the tenor Ian Storey.
I have not previously been to a Wagner opera either live or Live in HD. Although it was hard for me to put my finger on why, I did not like it. I think it was just that I found it incredibly ponderous.
Henceforth, I will leave Wagner to the Wagner lovers.
ETA: The production has been getting rave reviews such as this one. I can't disagree with any of the review. I just didn't enjoy it. http://dctheatrescene.com/2013/09/17/tristan-isolde/