I have leveled to 65 from 60 on a lot of my alts and I always use Ramps to about 63 mixing it with BF for the quests (worth doing) and then move to the Bone Waste instances, mostly the Mana Tombs which also has quests at 64. I use my druid to boost and the Mana Tombs is pretty decent for xp with only the second boss causing any issue (due to a stun and hitting hard even at 80 it can get a little shaky lol).
Once I hit 65 - 66 I normally just quest to 68.
I have heard of people bringing their toons to Northrend and grinding 60 - 70 on the rhino there and it has been posted here that it can be done in I believe 10 hours of play from 60 - 70. Remember Northrend mobs would probably give as much exp per mob to your group as a lvl 60 dungeon. Obviously you might have to compete for mobs in Northrend.