What's your favorite interface in adventure games? Doesn't necessarily have to be the most perfect or easy to use; just the one that you're the most partial to.
Off the top of my head, a couple of low-hanging fruit suggestions (feel free to add more):
LucasArts "9 verb" interface (Monkey Island 2, Day of the Tentacle, etc.)
LucasArts "verb coin" (Monkey Island 3, Full Throttle)
Sierra "icon bar" (King's Quest V, Space Quest IV, etc.)
Revolution "Left does/right looks" mouse buttons (Beneath a Steel Sky, Broken Sword, as well most Wadjet Eye titles)
Mine is actually the one in Leisure Suit Larry 7. You click on something and up comes a contextual menu of appropriate verbs. If it's a door, you can "open" it; if it's a button, you can "press" it; etc. — and it also has an optional text parser for inputting your own verb.
I really liked Broken Age's interface, but that game is pretty in every aspect. A simple collapsible inventory and conversation options that will just use the item you're talking about without additional clicks. Lets you focus on puzzles, story, and art.
An interesting point was brought up by Highbury on Twitter when I mentioned this topic (link to thread) about convenience vs freedom.
What is the purpose of a good UI? Are adventure games about giving the player unlimited freedom to explore (which necessitates more complicated interfaces), or is it about making it easy for the player to navigate the story — at the expense of railroading the player with limited options for interactivity?
Discuss. :)
(I was going to add screenshots of the tweets but I can't upload images to this board anymore, for some reason... I keep getting json errors.)