The whole "good melee and ranged" thing is going to wear off at about level 20. At that point, if you're trying to do both, you're going to be much less effective and slower leveling than if you focus on one or the other.
As for which one to go with, there are two routes you can take:
1. The "I want to have fun route". Do whichever you want. If you prefer the ranged caster aspects of the Shaman, then go Elemental. If you prefer the up-close melee aspects of Shaman, go Enhancement. If you like healing, go Resto.
2. The "fast, efficient, effective route". Enhancement. In order to keep up with Enhancement's damage output, Elementals will have to drink constantly throughout the entire game, even after you get Water Shield. Because of that, Enhancement grinds/levels faster, especially after you reach 40.
If you're looking to have fun, do whatever you want. If you want to get to 60 or 70 as fast as possible, go Enhancement.