you could acid stain them and clearcoat

I would have someone that does decorative concrete come in and stain the concrete or do an overlay that looks like tile. Then I would use plush rugs throughout.

Are you willing to do a little work to save a lot of money? I had a patio once that was cracked in several places so adding new flooring wasn't an option. So instead, I first painted the whole patio grey, then I marked off every 12" on all four sides, connected the marks with painters tape and painted over the grey with a terra cotta color. I sealed it well, and everyone thought they were brand new tiles!