I have a plan to put related classes into one file. This idea came from The Prowler's Datatype module and when I was programming similar type of stuff in Brick Atelier. I noticed that it's somehow easier to manage code and even design inheritance when there are less source files. It's maybe something we were not told to do, but I'm doing it anyway.
It's not a big refactoring which is something I try to avoid these days. It's more like re-arranging code into bigger pieces. This works with small classes, but not so much with bigger classes where actually splitting the class is a better option as mentioned earlier with the Level class saga.
I also try to use more inheritance which sounds quite obvious with a C++ project, but it's something I guess many programmers try to avoid (for no good reason). If you have a class-based code it's almost better use inheritance, because then you are going to remove some similar, repeating code for sure.
With content I try to design level themes from basic terrain topology first and then moving into details. I have some new ideas and tools to create difficult level themes so let's try it and see what happens.