If you do a little reading on these forums, you'll notice that there are a lot of folks that have done the 1-60 grind with 5 Shaman, 1 Pally + 5 Shaman or similar numbers.

It sounds like nothing hits hard enough until heroics to really warrant a dedicated tank (that is, assuming you do things below your level slightly).

Once you get into the fun 70 "endgame" instances though, you'll probably need that tank.

I'm not sure if you understand the instances and how they work, but mainly you want a tank, a healer, and dps. In 3 of your 5 suggestions you are missing either a tank or a healer, so....not sure how you expect to solo instances. But good luck either way! =)