I’ll be doing the same for our next game, so subscribing to this thread.
However, I will mention that to save time making this game, we have considered instead doing it like “Impossible Mission” - the classic Commodore 64 game. That means, we design a bunch of small room levels that are always the same, and we connect / arrange them randomly on the map every time you start a game. So you never know which room is where. You may want to consider something like that yourself.
This just makes it seem very limited. Because the difference in procedural generation and hand-editing to “randomize” is that eventually, players will notice the routine. When its procedural, it looks truly random.
I wouldn’t be too quick to dismiss the pre-made rooms approach that @jerotas suggested. I remember an article on how Fallout’s and Skyrim’s levels were built using basically the same approach, except that in their case level designers hand assembled the dungeons from parts (or kits as they called them). Here’s the link: