Also, a couple of quick examples of how the shapes could easily be redrawn to depict rough caves, which could be mixed in with the more refined blocks.
I've also been thinking about visibility. For example, maybe I only check for doorways when they are within visible range (line of sight and lighting). For example, if the party enters that L-shaped room above from either end, they won't be able to see if the other end has any openings or not, until they get into the middle area. They may find it's a dead-end, but they may not even discover that until they've completed any encounter in the area first. Maybe light sources could affect what's visible as well. Creatures and characters with abilities to see in the dark wouldn't be affected, but others would only be able to see as far as light sources allowed. This is where candles, torches, lanterns, magic lighting, ambient or carried by the party, or even floating lights that can be sent around by a magic-user could all play a role. Still, I would want to keep it simple. Maybe something like, candles can light 1 "arena" (as they are called in OSH; and which basically correspond to one 5 by 5 tile in my geomorphs), torches 2 arenas, lanterns 3, magic - depends on the magic. I found some simple templates for tracking how many turns/rounds/what have you a torch or light source lasts. Some things can douse the light, temporarily or more long term. Torches and other light sources may also be found in the dungeon. For now I don't expect a dungeon adventure to last so long in game time to make food or water much of a concern, but in the event it could be I would lean towards simple rules for that as well. These kinds of resources do provide opportunities for things to go wrong or right, stuff gets damaged or stolen or lost, other stuff is found along the way, etc.
Of course, it's all too easy to make things overly complex, so to start out at least, I think I won't worry about lighting and just assume there is sufficient lighting one way or another. Line of sight visibility should make things interesting enough for starters.