You'll love SDSU.
For apartments, the best place to go is with one of the bigger companies in town, as there are a LOT of slum lords in Brookings. I'd recommend
Welcome to Moriarty Rentals, Brookings, SD -- 605.692.6333 (little more expensive (by Brookings standards) but great management/fast service and repairs) or
Mills Property Mangement, Brookings SD (about the same as Moriarty). There are a lot more places, don't get me wrong, but these are probably the 2 biggest and also with websites to actually get more info. Then there is the sdsu's website for off campus housing, which I had used once to find an apartment.
Housing Listings
For your fiancee, I'm sure a few things are available in Brookings, but the BIG one is Daktronics -
Daktronics is a World Leader in programmable electronic signs, electronic and digital displays and scoreboards. They are the biggest manufacturer (in the world i'm guessing) of the big LED jumbo screens at stadiums and everything else. They definitely hire a lot of graphic design people. If you've never heard of them before, check around online, and I'm sure you and your fiancee will be excited about that place.
Hope this helps!