I've hit level 42 with my destruction mage, but more importantly, I have reached Destruction 100. I blast my way through most enemies now, and taking down a dragon isn't too hard as long as I don't run out of healing.
My Kajit sneak/assassin is level 22 or so. It's interesting to see that you can never be quite sure which enemies you can take out with a sneak (x3) arrow and which ones will be hurt, but not dead and yell alarm. I still have to fight way more often than I want to. But it is fun sneaking through an entire dungeon and murdering everyone from behind (x6 sneak bonus on melee attacks) without anyone noticing a thing.