Star Wars Land and Marvel Universe.
They would be two separate parks, each coming with themed hotels centered around the park.
Star Wars LandI can already envision the Mos Eisley Cantina, a restaurant with many different foods and a live (Anamatronic or Cast Member) band of those alien guys we all love.
A cool ride could be one where you board the Millennium Falcon and take a trip with Han Solo and Chewie across the Galaxy.
A cool attraction for this theme park could be Jedi Training and Sith Training. Kids could go through a series of obstacle courses, using their lightsabers and the "Force" (Using motion technology, you could create the illusion of the force, stuff like opening doors and the like). At the end, you could be awarded a badge of the Republic or Empire, depending on which training session you attended.
The park could be divided into multiple worlds, like Hoth or Tatooine. There could be flight simulators for Jet Wings, where you can actually control it, like a video game, but you are inside a vehicle with screens surrounding all the windows and motion mechanics on the "vehicle" to give it a realistic feel.
I am too lazy to do Marvel right now