I will also recomend Spartan Corner (It's a block from our house!) It's on the corner of Grand River and Abbott, they had a sidewalk sale last week, so maybe you can find some good deals still!
We also have three malls in town (nothing too great) Meridian Mall in Okemos, Eastwood Town Center, and the Lansing Mall.
Lansing there are also lots of fun little shops and places to grab something to eat Along Grand River.
Campus is usually filled with people in the Beal botanical gardens, 4-H childrens garden, and if your in campus you can't skip the dairy store, it's attached to Anthony Hall. Or go by the river and feed the ducks
(We LOVE the ducks!)