I keep them as a reserve. Always carry one staff in my inventory. If I run out of magicka and don't want to use my potions I simply use my staff until my magicka is regained.
This^
The one I carried with my first character was a staff of chain lightning I picked up in a quest from some bad guy (I forget who). It was invaluable in beating one of the daedric quests where you're confronted with the summoned daedra at once. I got killed like 5 times before giving it a shot and it took care of them nicely. You can use a spell for the same thing I guess but in that situation your magicka would have to be through the roof to get the job done unless you had a ton of potions.
I thought the Wabbajack was cool at first but the fact that you don't know what it's going to do makes it next to useless in battle. Turning an icewolf into a chicken was funny but against three angry Falmer, not so much.
Right now I carry a summon daedra staff but haven't used it.