My main hook for the map was A site. I used a layered bombsite where terrorists could take control of the upper levels and then spread into the middle without having to engage with A. Or they could drop past the upper level into an exposed firefight with defending CTs.
A site turned out well, the area that gave me the most trouble was A long. A long was a challenge as I had to work out how to connect the height difference in a way that meant timing worked well. The rest of the map was relatively fun to play.
Tomb was my first map I had tried to detail with a theme in mind. The end result was very rigid, but I learnt a lot over the time I spent developing it.