I think everyone forgets how flexible the free tickets are as far as stopovers etc...I did a year ago in biz

atl-ord
6 hours for lunch with friends
ord-CDG-LYS
23 hours to explore LYS
LYS-BCN
4 days
BCN-MAD (on DL metal...one of only two local pax--they gave me some hassle at the checkin and had to check with the ticketing office)
4 days
MAD-ATL

I was playing around with the DL timetable and was wondering if you could do a creative segment award run with some of the weird AF flights like

AGP-DUB
DUB-London
et cetera

Also don't forget to add the extra leg onto a flight which you're terminating in one of the hubs....an open jaw is permitted!

Choose one of the Airtran cities (LAX, LAS, DEN) and get a second vacation for the cost of a one-way ticket!

(ticket ATL/CVG-Europe-ATL/CVG STOPOVER ATL/CVG-DEN/LAX/SFO in the future)