Some people from the "Adventure Game Scene of the Day - Wednesday" thread might be interested in this.
I'd guess that this is the list of adventure games Sierra made with separate EGA and VGA versions, based on some research at MobyGames:
-King's Quest V
-Space Quest I remake
-Space Quest IV
-Police Quest III
-Leisure Suit Larry I remake
-Leisure Suit Larry V
-Heart of China
-Conquests of the Longbow
-and the quasi-adventures Castle of Dr. Brain and EcoQuest I
If there are any I should have noted and didn't, please list them below.
Also, based on a post of mine in an earlier thread, I've created
a page with a lot of screenshots from Space Quests 1 and 4, EGA and VGA.
I'd put pictures from more diverse games up, but these are the only Sierra games for which I have both 16- and 256-color copies to compare, and I'd rather not steal MobyGames' pictures.