You can create one set for DC and one set for Marvel. Try to keep it semi-realistic (i.e. Lego doesn't make sets with a dozen mini-figs, for example, and unless it's Star Wars, they rarely go above 1500 pieces).

DC:

Black Manta Attacks!
Mini-figs:
Aquaman
Aqualad
Mera
Black Manta
2 x Mantamen

Elements:
A large Manta sub with cockpit, airlock, and brig to hold prisoners
3 sea horses for the heroes to ride
A shark, octopus, and dolphin for Aquaman to command

Approximate Size:

Probably a larger box set along the lines of the Batwing set out now, but not the truly big sets.

I'll do a Marvel one later.

Brainiac Attack!
Mini-Figures:
Clark Kent
Superman
Lois Lane
Jimmy Olsen
Brainiac

Elements:
Daily Planet Building (upper floor and Globe top)
Brainiac "head" ship

Daily Planet could include a supply closet/elevator with a "quick change" feature for Clark/Superman (similar to the Batcave)
Globe would spin and could open to reveal monitor station/missile bank

Brainiac ship would have opening cockpit tentacle arm(s) to "grab"
minifigure, and launching missiles

Brick count
(honestly I have no idea how they would calculate that but it would most likely be comparable to the Batcave set currently out)



I have no interest in Marvel outside of Daredevil and Hulk so anything that incorporated them would be nice.

Perhaps a small rooftop battle with a thug or Hand ninja for DD and a Hulk Smash set with a tank or vehicle that could be given "damage" ... Both would be in the $10 price point boxes I would think ...

Legion of Doom

Superfriends Swamp Helmet style-- 120 Price point-- (Black Pearl, Turbo Tank Scale)

Would open up in the front to play room inside-- and include a Bat Swamp Speeder

Solomon Grundy (wampa sized)
Gorilla Grodd (wampa Sized)
Captain Cold
Sinestro
Lex Luthor- Purple
Cheetah

Batman
Flash

Sentinel Attack-- Large in scale Sentinel with Minifigs (since this thing would be large and lots of purple bricks-- probably 80.00)- I tried to pick figures that make sense- not neccesariy figures I want-- (if we never get storm or cyclops Im good)

Includes
Colossus
Shadowcat
Nightcrawler
Storm
Wolverine
Emma Frost

X Mansion-- 120 Price point
Open up space -- to Play (set up to include spaces to attach an eventual Danger Room and Blackbird Landing Pad module Sets (like the Cloud City Set)

Minifigs
Prof X
Iceman
Jean Grey
Angel
Beast
Cyclops

Magneto
Juggernaut

HEY! I said ONE Marvel.

I'd totally buy the Legion of Doom set BTW.

Shellhead, I had the very same idea about an Aquaman Lego set! Cross your repulsor-laden fingers.

My MARVEL set would have to have Venom and Sandman minifigs. I'm still miffed that we never got Spider-Man 3 Lego sets. I'm certain that comic accurate Spidey sets are allowed now, however.

My DC set would include a comic accurate Green Lantern. Leave out the SDCC movie version. Even better would be Hal, Guy, Kyle, and John minifigs with transluscent green constructs. Think of any Lego accessory or weapon from the past thirty years and make it green!

Sorry I couldn't be more specific.