Druid is a very viable choice too. Yesterday when I was questing I wasn't really paying attention to the "continue quest" and "accept" moments and spawned an elemental 5 levels above me. I still soloed it without too much difficulty.
The ability to put out some reasonable DPS as well as being able to shapeshift and heal yourself mid-fight gives you a lot of survivability.
Not to mention you have a lot of useful extras. For instance you can get through dangerous areas stealthed like a Rogue (In fact when outdoors I can move a lot faster than a Rogue when stealthed) you wont run out of breath underwater and can actually move quicker than any other class so you can actually outrun the aggro. You have Hibernate for crowd control when fighting beasts. You can cast Innervate on yourself to top up your mana. As a Feral Druid this pretty much eliminates the need to bring any mana drinks when soloing at all.
All this and we get good invite rates to instances and raids too. Admittedly mostly for healing duties, but hey. We can do that too.