When it comes time to use the expansion plot at the rear of Dark Universe, it would be great if they used the limited space left by building a stacked show building for two attractions.
For the lower attraction, I'd be happy with a Creature From the Black Lagoon boat ride that doesn't require massive sets, but rather uses tight, compressed spaces and darkness to create suspense (I went on a kayak tour of a Key West mangrove swamp that was very tight and would be great inspiration). I never went on Disney's Extraterrestrial Alien Encounter but perhaps the kinds of sensory effects of that attraction could be implemented within boat seats/ride vehicles to make it feel like you are under assault while venturing into the swamp. A few drops in the dark would be great.
For the upper attraction, I'd like to have a "classic family dark ride" based on Dracula, with suspended ride vehicles similar to Peter Pan's Flight but with some exciting suspended-coaster type drop moments as you swoop down out of the dark into a village. Like Peter Pan's Flight's London, if love to fly over a model of a scale village before flying down through the streets. (You would load the building at ground level and fly up to the second floor show building area, swoop through scenes, then dive down at the end to get back to ground level.)
The two-level show building -- which would be taller than most show buildings and probably similar to Guardians Cosmic Rewind but stepped back like a wedding cake -- would have a rugged mountainous rockwork facade (similar in scale to what Cars Land at Disney California Adventure has). It could have an icy snowcapped feel to add a chilling vibe and likely be distinctive from the mountains which will be behind Disney's Villains Land.
Here are some images of the two level show building and rockwork.