[Update: Fixed my 'Compilation/Collection' typo below - Thanks to @beckfield for this.]
Aside from expanding the new web-interface universal search to the Roku, I would REALLY REALLY LOVE IT IF THE FOLLOWING FEATURES WERE ADDED TO PLEX ON THE ROKU:
1. SURFACEABLE GENRES AND COLLECTIONS: I wish there was some way to surface genres and collections to the level of playlists or a library. (See mockup below). I want to access those all the time, but as it is now, it requires a bucket of button and arrow pushes to view a genre or collections. These are buried so deep in the interface that I didn't even realize they were there for months.
2. REMAKES: I wish there was some way of indexing remakes. In the same way that you can use collections to put together, for example, Shrek 1, 2, 3 etc. I want a way to index movie remakes. Eg: (Shop Around the Corner and You Got Mail), (King and I and Anna and the King). I have 52-ish remake sets (some movies have been remade 3, 4 and 5 times) that I wish I could index somehow. And, once done I would love for that to be surface-able in the same way I requested in point 1 above. I have contemplated using collections for re-makes but I already have SO many collections. I don't want my remakes mixed in or collection sets would become seriously bloated.
3 ACTOR FAVORITES: I wish there was some way to indicate favorite actors. There are about 150 to 200 actors I really care about. When I used to index my movies manually in Xbox and Windows Media Player, I sorted them all (manually) by my favorite actors. In Plex on Roku there are literally thousands of actors that one needs to scroll through to find favorites. That's too much. I know, for example, my wife would never use the current actor search method. I guess if/when the universal search like the one in the web interface is enabled on the Roku that would go some way to solving my issue, but still, that will require alpha-numeric key presses vs a quick up and down scroll of a favorites list. Would also love the actors faces to appear in the favorites list so I can just scroll up and down and look at faces of my favorites.
4. DIRECTOR FAVORITES: See point 3 above, rinse, repeat and apply it to directors! ;)