Shelly:
Thank you for doing research on behalf of your son, and an even larger thanks for his service. My brother-in-law is also in Iraq right now and is planning a trip to Disney after his return, too.
Although you didn't mention it, I am assuming your son is in Iraq with a branch of the military. If so, in my opinion, I would strongly urge him to consider the special offer Disney has for military families this year. All the details are
here. Not only could his family qualify to stay at the affordable Shades of Green resort at Disney (or many other resorts at 40% off), but the family will also receive deeply discounted tickets to the parks! I don't remember another time when park tickets were so affordable! The children, in my opinion, are at the perfect age where they are old enough to comprehend a visit with Mickey and remember their trip it but still young enough to really appreciate all of the "magic." There would only be a handful of attractions they may not be tall enough to enjoy.
There is a military discount with the cruise line, but you'll need to call (800) 951-3532 with the booking code MTO. In general, the cruise vacations are usually more expensive. If cost is not a consideration, the cruise has many pluses to keep in mind: less walking and more relaxation than a vacation to the parks alone not to mention children's activities for the kids so he and his wife can have some together-time. My fellow Disney mom Karen has been on several Disney cruises with her family: feel free to visit her via her bio page if you have more questions.
Wishing him and his family a magical vacation!
Whitney