As the title says, we took down the Lich King. It was not however all that easy. We could have made it significantly easier from the beginning by inviting two additional people, which we eventually did.
The kill took quite some time for a number of reasons. The first was that we kept wiping in the second phase. We were only using one healer, and it was a bit too much.
The second was that Blizzard went all fucking laggy and we had to sit around until it was fixed.
After that, we invited two people (a Shadow Priest and a Resto Druid). The Druid was on another server, so we had to wait for him to make his way to the instance. In the meantime, I opened Diablo 3 and made about 50k doing Dank Cellar runs.
Once everyone was there, we killed the Lich King on the first attempt with mostly no issues.
Next up for out group is probably Ulduar as I love that raid and have never completed it (I have actually never finished more than the first half of it).
I think we may start doing all of the content we have yet to see, probably going backwards from Wrath to BC to Vanilla. The list is fairly long of instances that people in our group may not have seen.
Ulduar, AQ 40 and 20, The Eye, Magtheridon, and Gruul to name a few off the top of my head.