The obvious choices
Humans are a given, but I'm curious to see whether or not BioWare will include subspecies as an option for humans. The reason being that Star Wars -- particularly in the Old Republic setting -- has a ton of subspecies roaming around and getting involved in the affairs of the galaxy.
Take the Miraluka for example. This species looks exactly like humans with the exception of their eyes, which are empty sockets. Anyone who's played KOTOR II will remember the seer Visas Marr, who indeed was a Miraluka. Their trademark appearance is their tendency to cover their eyes with something, and they can actually see the Force aura of the Jedi and Sith.
What I'd hope to see is some kind of subspecies option during character creation, where you can choose a human and then switch a racial trait for something like what the Miraluka have -- something that would allow you to feel like that species through a game mechanic. It probably won't happen, but it'd be a nice way to cover a lot of species in one swipe.
There's no doubt in my mind that we'll see Wookiees, and actually if they didn't make an appearance in the game I'd be shocked. With that said, I do feel the current class picks are something of a conundrum when it comes to these shaggy powerhouses. We know there'll be Wookiee Bounty Hunters, given that Treat of Peace prominently features one, but what about all those other classes?
Chewbacca wasn't really a Smuggler, since Han had that covered. No, he was more of a mechanic type. I'm not convinced that a dashing and charming Wookiee exists, though I could be wrong about that. Still, it remains to be seen what other classes Wookiees would favor.
I'm also curious how the voiced scenes would play out. Won't the endless growling and guttural voice rolling get just a little agitating after a while? Who knows, maybe there'll be optional personal translators so you can hear your Wookiee character speak in a nice English accent. That would be an interesting way to play the game.
We've seen some screens of these guys, although they're not as widely known as many of the other races. Still, I think there's a definite allure towards the Kel Dor, especially for Sith players because of their somewhat sinister appearance due to their required breathers and goggles. The Kel Dor had long since discovered the force before joining the rest of the galaxy, which gives them an almost sage-like lore. Come to think of it, they actually have a group of sages called the Baren Do Sages, so yeah.