The biggest highlights of our honeymoon were:
-Stay at the Poly (be sure you splurge, if you can, & stay at your dream resort!). We stayed club level, so we were extra pampered

-Go to the Hoop De Doo Revue-it's not romantic, per say, but it is tons of fun!
-Eat at a very romantic restaurant. We ate at the CA Grill, during Wishes. It was really romantic

We also ate at San Angel Inn, at a table overlooking the "river."
-Plan to spend at least one day not in the parks. Sleep in, book a late breakfast ADR, resort hop, relax on the beach or by the pool, etc...
One thing I wish we had done was book one of the backstage tours.