After Scarlet Monastery Cathedral I moved on to Zul'Farrak where I just cleared up to the graveyard and witch doctor (skipping the overseer) and reset. I repeated this several times to get to level 43 where I did the stairway event for the first time which was a lot of fun. At about level 44 I was able to kill the last boss, whatever his name is, after the stairway event and with a little luck I could kill the overseer. At 45 I was able to reliably kill all the bosses in Zul'Farrak and clearing to the final boss took about an hour.
A couple of notes about these last few levels. One, I got 3 epics, each at a 0.25% chance per ZF run. :D
Jang'thraze the Protector + Sang'thraze the Deflector = Sul'thraze the Lasher
I got 3 of each half putting a pair on my warrior, my paladin and my rogue. Unfortunately the rogue already has a better main-hand so it's just for show, especially since he can't use the two-handed epic. The warrior currently dual wields them since I can't equip the epic until level 50 and the paladin has converted it to an epic since he has a better main-hand already.
Another neat item in Zul'Farrak is The Hand of Antu'sul, a little newbie version of Thunderfury. :D It has an almost identical proc as Thunderfury, just less of a slowing effect and lower damage. I have two of them, one on my rogue and one on my Paladin and between the two of them it procs fairly often.
After farming Zul'Farrak until I got all the loot I wanted (a second set of Big Bad Pauldrons was the final item) I went back to Uldaman. I only cleared Uldaman once, mainly so I could say I did it but unfortunately the instance isn't any higher level then Zul'Farrak and the drops were none too impressive. :( I have now moved on to Maraudon and will be making my first attempts at it today. I have gone through the loot from the instance along with the levels of the creatures in there and it looks like I will be doing Maraudon for some time yet. The final boss is level 51 and there isn't much in the way of instances after that until Sunken Temple so my guess is I'll be doing it until about 50/51.
My quest to level 5 World of Warcraft characters at the same time.