Thank you & welcome to my TR! My husband loves to tell everyone that while Reid may look like him, he acts just like me.
This is a hard question to answer. Obviously, either vacation would be great, especially since it'll be a no kids trip. I think it all depends on what you envision for y'alls adult-only get away. Personally, before we had Reid, every vacation was go-go-go for us. Now, if we did an adults-only get away, I would want something more low key. I'm a commando type when it comes to WDW & I just don't know how to slow it down there. But, if you're not commando like I am, I could see where WDW could be relaxing for 2 adults.
Personally, because of how commando I am at the parks, I would choose a cruise for just me & Ed. It is super relaxing. But there is also a lot to do. During the day, you'll have the pools & hot tubs (including the adults only area), the sports deck, you could just find a nice spot to sit & relax. Even though you wouldn't have kids with you, you could still do the Midship Detective Agency - it looked like a lot of fun & I wish we would've had the time to do it. There is a cool art gallery to walk around. Then, of course, when you're in port, you could always go on port excursions. Also during the day, there are TONS of activities offered on the ship, including many that are for adults only. At night, you'll have nice, quiet dinners. You can stick to the main dining rooms or even try out the adult-only restaurants (Remy & Palo on the Dream). I believe they also do brunches in those, but I'm not positive. Then, you have the shows at night as well. And the adult clubs seemed like really nice places to sit back & relax. Oh, and there is the Buena Vista Theatre! This theatre shows Disney movies during the day & night. They offer a good variety of movies & a lot of them are current. I really found that the ship has a lot to offer.
Again, either way will be a great vacation for the two of you. But, personally, I would choose the cruise just because it is very relaxing with still a lot to offer to keep you entertained. I know it'll be hard to decide which way to go but once you do decide, you'll have so much fun planning & getting ready for your trip. Good luck in your decision making & let me know if you have any other questions!