D&D 3.0 and 3.5 each had a movie to go along with their releases. I'd wonder why there is no similar movie for 4E's launch but its an easy guess that they previous two movies didn't make enough money. But if you were in charge of coming up with the basic concept of the 4E movie, what would it be?
Well, neither movie was made by WOTC, and I know the first one was more-or-less made over their objections, but there was no way to get the rights back. (I remember that when it came out, some ranters used it as "proof" WOTC was eeeeevil, because the movie was "their idea of what D&D should be". (Whereas now, we know, WOTCs idea of D&D is Dragonball Z.)
ANYway...
First thing I'd do: Not hire a Wayans.
Second: Use one of the settings which has real character. Spelljammer or Planescape or something, something which can't be filmed in some former Eastern European nation using a bunch of ren faire rejects.
Third: Keep pounding on the script until you can get in a true D&D flavor without intolerably forced and painful expository dialog. Peter Jackson managed to convey immense amounts of LOTR backstory without ear-splittingly bad dialog, so can I.
Fourth: No pathetic "comic relief". If there has to be one, it will not be a charmingly greedy rogue, absent minded wizard, stupid fighter, or lecherous bard.
Fifth: Hell, just hire Rich Burlew. OOTS is not only a hilarious gaming comic, it's turned into a great, dramatic, storyline.