Visiting things that used to be difficult

Since our performance in arena has reached an impasse lately, the three of us that usually run together (DK, Resto Shaman and Boomkin) decided to try to do some other things for fun. Latley, we have been on an old raid kick...we have cleared Zul'Gurub, AQ20, Molten Core, and last night we did Karazhan. Most would say "big deal, there is no challenge in that," or "bah, I can 1-man those." That's perfectly fine - we did them for fun, but more than that, to be able to see areas that we never would have had access to in prior levels. And it was fun, not a chore! Some of the encounters still have tricks or gimmicks that make you have to stop and think. But they are easily surmountable. Some of the loot, especially in Molten Core, is still worth quite a bit on the AH, to people that want to collect materials to build a lvl 60 Legendary weapon, for example. So, it's even a bit profitable.

It's worth trying out, now that most are more than adequately geared enough to 3- or even 2-man these formerly difficult raids (MC used to require 40 people - and today only 3 can clear it!). What other things do you do to occupy your time if your primary pastime in-game is in a state of deadlock?