Delta will only allow on-line check-in if you have no bags to check.
On-line check-in works great if you only have carry-ons.
The Skymiles kiosk promotion runs through May 15, 2003. Unfortunately on my last 3 trips with Delta, they seem to be funneling all passengers to the kiosks rather than the ticket counter. So, the kiosk lines have been LOOOONG. I've ended up using the Medallion / First Class Check-in line for the sake of speed. I e-mailed Delta and let them know I wanted to use the kiosk to get the bonus miles but that their new policy (at least in Hartford, LAX, and Tampa) made the kiosk inconvenient. They comped me 1,000 Skymiles, which I thought was very nice of them.
Have a great trip!