I know the OP wants people to make a great case for Disney but in this instance, I agree with most everyone who has posted so far, when it comes to mancations, I just don't think Disney would even be in the running if it were myself and my guy friends. Out of the 4 choices you have presented, I would go with either Las Vegas or Chicago.
I have never been to Vegas but I do know that there is so much to do there that you could spend 3 days with a very minimal amount of gambling. You've got tons of places to drink, great hotels, tons of good looking people and compared to Disney you won't have as many families or annoying children to deal with. Only con I can see here is the weather, way too hot in the summer.
I have been to Chicago once and it was the middle of winter and I froze my ______ off but it is a great looking city and probably 1000x's better in the summer or early fall. If you were going in late August/early September, not only could you catch the White Sox and Cubbies, but may even be able to sneak in a Bears game as well. You could also charter a boat and go out on the lake if the weather is nice.
I have been on one cruise and would have to vote against this option only because if you only have 3 days it just doesn't seem worth it. There aren't too many places you could get to and from in 3 days, if you left from Miami you'd probably only go to the keys or the bahamas and then return and I think you'd be better of just going to the keys or bahamas if those are the only places you'd get to see. I would also say avoid Carnival, too many families with little kids.
If it does come down to Disney, I would call it an Orlando vacation and I think I would do everything BUT go to the parks. I just spent a week in the Disney area and never once went to a park and had a great time, there are plenty of bars to go to and once you are in the central Florida area the coast is a very short drive in either direction. You could go over to cocoa beach and charter a fishing boat for a day or do the same in Tampa. Also for those who do like to gamble there is a Hard Rock hotel/casino in Tampa. For a guys only trip i'd recommend Bush Gardens over Disney, less emphasis on princesses and more emphasis on thrills and beer. so to sum up:
first choice- Vegas
2nd- Chicago
3- Orlando
4- Cruise