It's true, there aren't quite so many choices for this first film as there likely will be in the remaining films.
I'd personally
love the front gates of Erebor, and another piece that shows off the interior, too. Those are my top wants environment-wise.
Love the Dwarven design aesthetic.
Dale would be great, but, like Erebor and Dol Guldur, I expect we'll see more of that in the remaining movies. Especially once they introduce Bard and his backstory. So those might be coming later.
Rhosgobel is definitely on my list. (The question of where to stop sculpting the tree will be an interesting design challenge.)
The Green Dragon is a must.
But that might be more likely to eventually show up in the LOTR line later on. Since it hasn't really factored into the Hobbit beyond a few wide shots of Hobbiton.
The Carrock would be cool.
I'd personally like to see them tackle a few of the new Rivendell locations, like the White Council's gazebo and Elrond's waterfall/crystal table room. It'd be great to get some small and mid-sized pieces again. Don't get me wrong, I LOVE LOVE LOVE my Rivendell and Barad-dur, but they do pose some financial and spacial ... eh ...
challenges.
I was really hoping that the designs for Goblin Town and Gollum's cave would be more striking and iconic, but neither really grabbed me as environment pieces I would be keen to collect.