I'd also go for shiny graphics. I always found this an interesting part of gamedevelopment. I've learned alot during the last years and I would like to take it to the next level and make something cutting edge.
However, I think I would also spend some time on audio programming. I've got some experience with OpenAL and I could easily add some more stuff to my audio module (chorus, reverb, echo etc).
Things like userinterfaces aren't a lot of work IMHO. If your game is not too complex, you can easily make a good UI for it that works intuitively.

@Dazappa: Yeah, cross-platform gamedevelopment is still quite hard at this stage. I feel GLScene is a tad too big to "just port" to another platform. There are other good projects that are maintained by individuals, who sometimes release a new version. Getting their engines work on Linux/mac is still a big task.
At the moment, I'm trying to get my own engine work on Linux. My goal is to have an OpenGL 3.x + SDL engine working on both windows and linux. So far, I'm stuck with OpenGL2.1 because the latest SDL release doesn't support OpenGL 3.x contexts. I did make my code forward compatible, so swapping to OpenGL 3.x wouldn't be too much of a problem.
I also know that Luuk van Venrooi is still working hard on his engine and demo's. He has a lot of experience with advanced rendering techniques. If we, and some other people, join forces, we could make a great framework. Like I said, I allready have a working audio module that can be used. Don't worry, There is still hope and potentional left in this community.