I would also count on future schedule changes that may make the whole itinerary invalid. If that is the case Delta is known for being accommodating with their own flights.
My original trip: PIT/ATL/AMS/TXL DL/KL/KL
Yesterday, I got an eMail of a schedule change in my award ticket to Europe for July 2010 giving me a goofy connection. THEN, a couple of hours later, when the ticket was re-issued, I got an eMail of the re-issue and it had changed AGAIN!!! I called and they couldn't figure it all out and couldn't find anything good for me. I told them that I'd sleep on it and look at it today. Well, I got another eMail later yesterday evening that I had been changed COMPLETELY to PIT/DTW/AMS/TXL!!! NW/NW/KL - - Which didn't have W class availability! Nice! Thanx, NW!
Changes . . . Changes . . . Changes!!! This is still 9 months away!!