http://www.gamefaqs.com/boards/192511-thief-ii-the-metal-age/61756687

My list. These missions range from good to amazing. Looking Glass would be proud.

Thanks!

I loved the design of Rocksbourg, but the random hypersensitivity of a lot of the guards/civilians really turned me off.
The 7th Crystal was not as good as all of the hype put it out to be (though it was nice to run through a mansion again).
Seven Shades of Mercury was... the best that I have played so far. I loved the premise of the different fraternities playing capture the flag on the backdrop of a serious post-Garrett (I saw it as post-Garrett) world. Really sad that it never got a sequel.

There are quite a few that I still need to run through. As well as fixing this issue with Thief 1 not letting me do DarkLoader.

Edit: Even though I was put off with Rocksbourg, the fact that I didn't finish it forced me to go back... I ended up playing through 1-3. It definitely improved, and I am excited about 4.
Perhaps I'll have to go back and try to finish Calendra's Legacy? I really hated the linearity in it though.

Double Edit: I finished Pirates Ahoy! More importantly, I finally finished Calendra's Legacy. I figured out what I was doing wrong and managed to rob the jewelry store. It was actually quite entertaining and I am glad that I went back and finished.

The best mission made is Ominous Bequest. There are threads on ttlg forums with lists of best missions, but the forum won't allow me post links.

A long single mission or campaign?

It is a long mission, however there is also a kind of sequel to it.

Kind of like Rocksbourg, I will look into it.

Any other recommendations?

I tried Keeper of Prophecies and got royally bored with it. It's hard to appreciate something when there are so many great designs out there....