I also spent a lot of time restructuring my inheritance hierarchy. Somehow, this led to a really nasty bug that has been in my code for a while but only surfaced after restructuring. Sometimes the program would crash AFTER I closed it, but the behavior was intermittent. The good news is that I became very good friends with Visual Studio's debugger. I still need to figure out where it debugs "from", as I could only get my game media to load if I used absolute paths instead of relative paths. The culprit ended up being a line in certain classes destructors:
SDL_FreeSurface( image );
I have no idea what SDL is doing when it frees surfaces, but I don't think my intuition was right in this case. My guess is that sometimes the program would try to access invalid memory or something as all the destructors were called (i.e. if a GraphicalObject frees an image that an EnemyShip is using as well, when the EnemyShip's destructor is called, there will be nothing to free).
I think I'm close to implementing the next set of features. Although I haven't made a ton of progress on the game in the last week and a half, I would say it has been extremely productive nonetheless.