Does anyone enjoy any suggestions as to flooring that would be relevant for a heated, concrete underground room floor?
Painting concrete is becoming more popular. Go to a place like Home Depot or Lowe's and they can show you the paint to be precise used for that along with the instructions on how to do it. I've seen it done and it's really beautiful. I've also seen it done where on earth they cut the concrete to make it look like 3ft x 3ft tiles and afterwards did the paint treatment. There is a sealer that goes on top of the paint so it won't chip and so you can use cleansers.
Tile other works nicely over a heated floor, and although it is time-consuming, it is somewhat easy to install for the average do-it-yourselfer. Tile is also suitable for a vault, as it can stand up to a bit of moisture.
Another newer option is the vinyl strip flooring that looks like a hardwood floor. I've see these installed, and it's really beautiful. It's also a very unforced DIY project. It's time-consuming, but certainly takes smaller number time than installing tile. It's also great because, if you were to damage a piece once the floor is installed, that one piece can be removed and replaced, which is not the bag with hardwood floors or laminate wood floors.
Answers: Acid staining is a great choice. Do a search for concrete stain or acid stain. Acid stain floors are some of the most lovely and unique floors out there. And you are using the existing slab which is apt for the environment.
Word of caution: If you have gas within your home make sure it is turned off since a contractor seals your floor. Some contractors have be killed by using a xylene based sealer contained by a basement and not turning off the gas and ventilate properly.
There are plenty of other sealer options out there that hold no vocs, such as epoxy or water based products.