DUO combinations for PVE

So I've read the wiki and tried searching the forums. And the wiki for duo combos I found was lacking some, and I did some searching but didn't find alot. I would just like some opinions from dual-boxers. What I have is 4 70's (hunter/shaman (main/melee)/warr/lock), 61 pally, 60 mage/priest/druid, 50 something rogue. Now out of the 60's I have what would be the best combo to level up to 70?

Also, once 70 what is the best combo for running lower instances, whether for rep or for shards? Or best for farming right now i solo the top of BT with my shaman, but I see pallies run in there and round up more than i can, I have no downtime, but would love to be able to do more than I do. At this time I don't plan on doing 3 account s(i do have a third for the raf but am not going to pay more than the 19.95 to activate it to get the toons up to 60). I'm willing to respec the shaman and such (i do have healing gear from KZ, my melee is badge, MH, SSC, or ZA).What i was thinking when WOTLK came out was go Shaman/Deathknight (tank for deathknight). Would druid/shaman be good? I like having fun playing, as it is I get teased for too many alts, but once I level up the mage or priest or druid I prolly want to focus more on farming/instances and such, i mean I will probably go back and level the other 2 60's to 70, but maybe not before LK comes out. (yes i ramble, i get told that all the time) would ust like some ideas and such.

To me, the whole point of MBing is to experiment - it's not the goal, it's the journey. :)

You have a lot to choose from, I would try them all, and see what you like. Also, why not level them ALL? Each instance is different, in regards to mob, so what works for ramps, may not work for slave pens. Know what I mean?

There's no "best" duo, it's all down to what you like, what you're good at, and how far you're willing to go with them. You admit you like to have lots of alts, so go with that - level all of them, when you hit a wall, swap one out and try another combo. You have choices, which is good - why not set a goal of having one of each class, so you can find out which combo is best, for you?

It is my goal to have 1 of each class. And yes level them all, just seems daunting right now, yes 1-60 is very easy right now, but i remember that the 60-70 wasn't as fast (although my pally benefited from the RAF level up wish I had not leveled my mage to 60 doh cause that gets you 1 more level (well close)). Although I prolly won't level my rogue, i have never been a rogue person, people always ask me why my shaman wears leather, and I joke I'm a rogue in a shamans body (in reality blizz hates mail melee i think, all good melee gear is leather (there are some exceptions)). In fact the only mail i wear is the bear sholders from ZA and the chest piece off H MGT. The elitist jerks numbers for determining which gear is best for PVP backs me up (in fact I was in a TK raid the other night with a diff guild my friend knows and the melee shaman there had same level of gear but was all mail, I smoked his ass), anyways, again I rambled off topic.

I just guess I want some combo that can burn 2-3 elietes if possible and live and not have tooo too much down time.