I am doing my first run through of the game since last July, filling out the map and checking out all the cool new detail that has been added in my absence. I did the initial levels of Steps of Torment and have my first Skeleton Key now. I am wondering if it is worth doing the Rogue-like portion of the dungeon or if I should save the key for later on where I can get high level drops. My gear is nowhere near optimal as I am starting with a clean slate and I am currently a level 33 Cabalist. Would I be able to complete the run? Is there any cool new architecture to check out down there? Would I just be better off saving the key for later? If it matters, I do have the AoM expansion but not the Crucible.
Any tips or advice would be greatly appreciated!
You will get more and better items just by progressing through the story and playing through elite. Save your keys for ultimate.
Cool that’s what I thought, thanks! Just wanted to be sure I wasn’t missing any jaw dropping improvements like the outdoor undead ruins in Act 2.
I used to save chests and all. But the thing is, that I can make almost any number of keys at Ultimate level. And the right piece of equipment can make life at lower levels a lot easier (eg. Devils Cage Hauberk on all my characters). So now I just open stuff as i come across it.
How you want to do it is up to you. And no, you are not missing much af architecture on the last two levels of SoT. Except for one room that is a bit special but you will find out eventually… 
I do end up using that piece with astoundingly high frequency.
If you do not have access to mandates then completing the Steps of Torment will help you to increase your reputation with the Rovers. Other than that I like to try out new chars in the rogue-likes, too.
Only if you want some specific MI for specific build
Also running a Bleed-build, like Shonobi of Cairn (sorry Fluff) makes SoT intresting.
Still it’s the first true test for build so why not, Skeleton Keys aren’t really that hard to make and the MI gives you nice mobility.