This is what I did today.
Those tiles are bigger than they look like, at first glance. They're 18" by 18" tiles, very thick. We'll be putting in similar colored grout when they've cured. This is roughly 1/3 of the room, but the fireplace is about done (just pulled up the near corner piece to redo it.) . The kids are actually kind of helpful.
The mortar is the worst part. Takes a while to mix, and it takes a while to clean the buckets with the hose. The rest is simple repetition, and a powerful desire to see things square.