Mike, most man made tile is ceramic tile. This just means that it's made of clay and fired. Floor tile can be called porcelain tile because it's heated to a higher temperature during manufacture than wall tile. Floor tile is harder and harder to cut during installation because of this difference.
Leveling the floor area is the most critical part of an installation. If you do not have a good level and flat surface, particularly with large tile like you are considering, you will have big problems. Laying tile like this sounds like a job for a pro.
For what it's worth, our bathroom has a slight crown on the floor so water runs off to the sides nicely. It also is made out of very small hexagonal tile so each tile sees very little variation in thickness. This works well. I would not be able to lay the big tile like you are talking about without a major rebuilding and relevelling of the floor.
Personally, I would only consider big tiles like you want in a big room as a design factor also.