My main DVD system is not Roku based, but rather DVD changer based directly to the projector. I do have a bit of experience however since I wrote the DVD librarian that controls the changers and allows for simple selection of a DVD (Totally point and click)
In the system, a Philips iPronto acts as the part of the GUI that you touch, the main screen acts as the part of the GUI you look at. [Yes you do look at the iPronto to see what button to press]. The system has a copy of the DVD profiler XML data base at its disposal. When I get a new DVD I have the profiler automatically absorb it, and I manually add, via the profiler, a tag I defined as slot number where I wil store the DVD. For DVD sets I store multiple slot numbers.
The system will then bring up the DVD list in either Alpha order or reverse chrono (User choice) and put it on the big screen, 50 titles per screen image. Navigation is by N,S,E,W buttons, Page up/down, or if alpha sorted by first letter of the title. I saw no sense to showing covers as part of the library function. It is too slow and adds no real value. The name of the movie is what I want to select by. The system is smart enough to do proper text conversion for funny charachters, and knows how to expand sets into multiple entries with the set name followed by Disc 1, Disc 2, Disc 3, etc. When the desired title is selected, one either hits Play at which time the slot number is retrieved and the changer started, or one can hit Info that brings up the full contents (well most of it) from the profiler data base along with the cover image, puts it on the main screen so it can be easily read from the seating area.
IMHO after dealing with DVD's and Laser Discs for about 10 years, having a family in the movie industry, and hearing all sorts of ease of use ideas, I vote for simplicity (text titles) extensibility (full info) and automation (one simple process for adding a disc to the library).
I see no reason why this could not be a front end for the roku with slot numbers replaced by fully qualified addresses. XML is very flexible and easy to parse.
If there was a way of adding attachments I would throw up some screen snapshots, Maybe I will take some pics and add them to my web site.
My 35 cents