When fighting the Centurion before you get to Blackreach, I was running up the stairs, jumping down behind him, and running away and all over the place. The AI was so confused and could not get into a good position to fight me, and his steam could never reach me.
I also love those bow and arrow duels with a lot of taking cover and trading off shots and all.
Also, the columns at Nahrikiin's location come in handy, and I use to run all around them and come up on the otherside, attack him and do it again. Also came in handy when two dragons attacked me at that same spot.
Love it when giants chase you up a winding rocky path too!