Actually that would probably work quite well, although you'd be limited in the difficulty of targets you could take on. Shamans get blinds, as well as all their slows. If you pulled with the starfall clicky slow then overwrote it with a stronger one, or added a cripple-line debuff, that would generate a LOT of aggro. Throw in a blind and bam, you're golden, as long as the rogue doesn't fail too many evades.
Once you got to 60 and got the shaman's ancient: sotb, you could just throw on some debuffs and then take a nap while the rogue slaughters the mob.
Of course, on the flip side, you'd have a hard time with multiple targets if they were resistant to root, and wouldn't be able to react very well in emergency situations, with your shammy getting beat on.
As for pally/shaman and pally/druid... both are really, really good. When you get into the high end game, I'd say that pally/druid is at least as good if not better. Paladins have absurd survivability, between their AC/HP, their self heals, LoH, group hots, etc. That means they can really take advantage of the druid thorns. Pallies also really shine on tanking multi-pulls, while druids get an AOE root. There's nothing quite like duoing a pull of 15+ mobs and getting 1/3 of an AA with each character. AOEs on pally to get hard aggro, self heals and heals from druid while they beat themselves up on your thorns, and, if you need a break? Just PBAOE root with druid and back off, heal up, and go again.
Pally/Shaman lets you take on tougher individual targets, which is certainly useful. Shaman slows with a strong tank trivialize exp pulls, and on stronger targets, you can slow and DoT while the pally keeps himself alive, then you can keep heals going all day without breaking a sweat (or going oom).