Suggestions for tweaks...
Abilty to heal automatically when fighting within the vault. It is very difficult to manually heal your characters while they are in the vault.
Ability during combat to move characters during emergencies more effectively, I cannot count the times I have wanted to move my best fighter to a room where it is required and been unable to do so because the game will not let me.
Weird mechanics for wasteland travel, I had three characters in the wastes, two very decent fighters and one so so. The very good characters died first over time and the soso guy went five hours longer. Why? They good characters ran so much during combat that they effectively killed themselves. This to me is a huge balance issue that makes no sense. Perhaps I'm incorrect in my assumptions but perhaps not.
Good luck all!