We always try to do both Uni and WDW on every trip -- even if it's only a day squeezed in to either park.
But on those few times where we weren't able to spend a day at WDW (or a Uni park when we'd do exclusive WDW parks), we'd opt for an evening at one of the WDW hotels with a nice dinner, as well as cocktail hour. Go early, walk around, shop at the gift shop, grab a drink at the bar and have a nice dinner at, say, Jiko, Citricos or Cali Grill. I mean, you could time your dinner at Citricos or CG to coincide with Wishes.
DTD doesn't equal Disney magic for me, either. It's shopping time, usually for early Christmas presents. It's done on our last day, on the way home ... we always pack some Earl of Sandwiches in the cooler, too, as they're perfectly reheated when we get home.
So if you can swing it financially, I'd say plan an evening or two at Disney hotels.
FWIW, this past January, DH & I hit WDW for a four-day last minute trip and stayed onsite there. Ugh, we have to drive right by Uni and our hearts were breaking since we weren't going to be able to hit any of the Uni parks. We took an evening to spend at RPR and have dinner at Tchoup Chop, enjoy some Mai Tais in the Orchard Lounge, enjoy that awesome music they play in the lobby, got there early so you could still hear the Hulk whooshing. It definitely took some of the heartbreak away
