The actual corporate office in Green Bay is pretty nice. It's smaller than a typical corporate office so everyone is pretty friendly and it's very easy to get to know people in other departments. I've been here for a few years and everyone I've met has been pretty friendly. I moved here from out of state and I think it's a Wisconsin thing, but it is very easy to get a group together for happy hour any day of the week.
Dress is business casual, Fridays you can wear jeans for a $1 donation to the United Way. It's not a very creative atmosphere, but not too up-tight/corporate compared to other places I've been.
With it being as small as it is, there are lots of opportunities to work on projects you would never get to work on at a bigger company like Target, so a typical day is never the same. That might depend on which department and position you hold. You also get to see the results of your work fairly quickly as opposed to other places.
Overall, I think Shopko is a great place to work and would recommend it to anyone.