Well there aren't so much many iconic "vehicles" for superheroes except for Batman.
Though Marvel has a few potential vehicles (and some that sort of stretch the term "vehicle":
-X-Men Blackbird
-The infamous "Spider-Buggy"
-Quinjet (seen in the new sets)
-Fantasticar (Fantastijet? Whatever their flying car is called)
-Wolverine Motorcycle (seen in the new sets)
-Ghost Rider's Hellcycle (this would be cool to see in Lego form!)
-Hulkbuster Iron Man Armor
-Sentinel
-Helicarrier (not just the actual "scene" inside!)
-Any other S.H.I.E.L.D. vehicle
-Starjammer (this is slim-to-none!)
-Red Skull Car and/or Jet (from the Cap movie)
-Punisher van (loaded with artillery?)
There's also a lot of good places for potential sets:
-X-Mansion
-Danger Room
-Asteroid M
-Asgard
-Baxter Building
-Avengers Watchtower
-Dr.Doom's Latveria Castle
-Savage Land
-Negative Zone
-Any NY City scene featuring Spidey