At higher levels I don't rely on quests to level up, but just keep maxing out Smithing, Enchanting and Alteration. Smithing uses Nchuand Zel as a source of Dwemer metal (~200 per visit) and respawns really fast. Enchanting uses the Black Star and a Soultrapped weapon: after every human kill, recharge the weapon with the Black Star. Alteration use Telekinesis and/or Detect Life combined with armor and jewelry that reduces to cost of casting to zero. Not very exciting, but you can gain levels very fast using a combination of them.