I have been fortunate enough to visit the Louvre and frankly, within a half an hour I was looking for the way out. It may be my imagination, and please forgive the sacrilege but I felt a bit captive, much like a newbie in Ikea on a Saturday afternoon; there ain't but one way in and out of that place and if you lose sight of the arrows amongst the chaos, you're kind of screwed.
I'm not sure what about large museums exhausts me so...the crowds of people to negotiate, the echo of foreign language filling cavernous rooms, the pressure to understand the significance in each piece; or maybe it's just all that art and I'm an unappreciative cretin.
Whatever the case, have you seen The Google Art Project? It's kind of amazing, and the escape route is just a click away.
photo July 2010, Tierrasanta