I finally reached level 100 with Coriel. I also upgraded my garrison to level 3, though it took all my gold. I haven't touched the max level dungeons yet. My plan is to finish questing in Nagrand and then see what I want to do.
I did do the Bronze Proving Ground for healing to get a decent healing weapon. It was fairly easy. I haven't tried Silver yet. I did also craft my first i640 epic: a healing ring. The secondary stats are terrible, but whatever. I'll fix it after I craft the i640 necklace.
Spires of Arak
I liked this zone a fair bit. It did seem like a little bit of a side-trip, focusing on the Arrakoa instead of the Iron Horde. But I liked the mythology behind the Arrakoa gods, and also the legend of Terrok. As well, the followers of the Raven Mother were hilarious.
I disliked the goblin quests, but that's because I dislike WoW's whole take on goblins that appeared in Cataclysm. It's too anachronistic for my tastes. Gnomes are kind of similar, but they lean more to the steampunk vibe instead of modern corporatism.
I'm also not super-thrilled at what they did with Admiral Taylor. It feels like Blizzard saw the various complaints that Nazgrim was killed while Taylor was left alive, so they decided to balance it in the most ham-handed manner possible. At least Nazgrim got a good death, and sparked a fair bit of discussion and debate. Meanwhile Taylor gets killed off-screen by some random warlock. (And then becomes a ghost follower? Really?)