Try Monks, Minotaurs & Wolves or Zombies in the Edgeville dungeon opposite Vanakka. Take into consideration, they're not that bad xp at all, and they're quiet every time I seem go there.
With Monks, find an empty world, don't train with someone else in it.
I have also hit 74 Strength and I'm still training at Monks lol. Not bad xp at all.