My Morton barn built 12/2003 has both overhead door and sliding doors. Overhead is superior to the sliding door. The sliding door hardware seals it ok and it still slides well. You can get nice overhead doors that look like carriage house doors, here is one example that I found with a quick search:

http://www.fimbelads.com/images/full/ae/ae003.jpg
http://www.fimbelads.com/photo_gallery/ae_carriage_house_gallery_1.html


[Linked Image from i108.photobucket.com]