I just got my beta, and i've been playing. Did raynor for the tutorial, and i got Vallah for free.
So i'm playing vallah right now, been following a basic w spread guide and its working out fine.

What other new champs are worth the gold investment? (( I'm not about to spend $'s on the beta.))
I've watched some zeratul and i hear illidan is fun.. i'm not too interested in supports atm..

I'm also curious about the 3 vikings, but havent seen them in game yet.

Sonya is a cheap hero and easy to use. Give her a try

My first buy was elite tauren chieftain(2000 gold) and he's still my favorite. Depends on what you like to play really (tank, support, ranged) You can go to the shop and try out any hero to get a feel for them.

The lost vikings seem pretty difficult to play so I'd get some experience with easier heroes first before you get them