I loved reading your posts, and felt the excitement you are feeling about your "only" trip to WDW. But, if i may, i would like to offer some thoughts.
From my limited experience, i have found that the most important thing to bring on a Disney trip is the right frame of mind. From what you have written, it sure looks like you've got it - expecting magical memories, planning romantic moments. But because you feel that this may be the only trip you take to WDW, you are taking the chance that something disappointing will happen. At Disney, plans often go astray. Rides break down, transportation issues arise, crowds cause delays, and many other things happen that can upset a schedule. For most of us, if we don't get to see a certain attraction, well.... there is always next time.
But what do you do if there is no next time? Well, that is where the right frame of mind comes in. As you obviously know, Disney World really is a special, magical place. So relax, and just take in the magic. Don't let a mishap or change in plans alter your good attitude or ruin an otherwise great day.
Also, if you have a list of "must do's", i suggest adding the park hopper to your ticket. (if you have not done so already) Some see it as a waste of money. But to me, it is the price you pay for piece of mind. With the Hopper Ticket, a closed attraction is not the end of the world, because you can return on a later day if necessary.
In any case, just don't lose the magic, and you are certain to have the vacation of your life.

Here's hoping that this will be your first and last trip - without your children! And my final thought. I offer you best Wishes for a Fantasmic trip full of Illuminations!