oh man dude, lvl 67 with my 5 shamans was the most fun i've had in wow so far ... I burned through all my rested xp in instances so fast I couldn't keep up =)

I ran underbog, slave-pens and mana-tombs over and over from lvl 65-68 and it was so easy. Basic strategy was to LB the first of a 3 group, and immediately follow up with a CL, then 1 more LB and the first guy was dead. The rest of the group would have just arrived and I would thunderstrom them away and CL + LB another one. When they got close the 2nd time, i would earthbind them just out of range and and LB or CL again and the 2nd guy was dead, then thunderstorm and repeat. You can clear groups 6+ fast and easy that way ... my guys had somewhere around 450sp each i think.

For boss fights, i would throw 1 or 2 earth elementals down and full on DPS the boss and heal the elemental - he would hold aggro the whole fight. Tougher bosses got 2 or 3 elementals. My shamans are 70 now and I'm able to clear up to the prince in UK, but have only tried him once so far (got him down to 33% but didn't heal my elementals), but I believe is totally do-able. I was actually able to clear up to the boss in UK at lvl 68 but had to blow 1 elemental for each drake fight.

I totally recommend burning your xp by running lower level instances, but like thinus says, they are good enough to run almost all instances. I bet I could have done steamvaults at 67 ... good times. You obviously need a shield equipped in your off-hand to be able to survive in instances - just in case it skipped your mind =)

Forgot to mention - have you done ring of blood? Get someone to help you tank it, and get that mace for your shamans. That quest line has great xp and $$, and a good reward for a short time investment.