I have used these matts in my classroom when I was teaching and yes they get dirty but they are easy to mop and vacuum over and much better then my floors getting destroyed,and nice to sit on when playing, for me as well!
I have them in my laundry room as well which is cement and they are awesome, much better then cold concrete!
I'm my playroom I have ones that look like wood in my dramatic play section, and multi-coloured ones in the free play, blocks, little people area.
I like the suggestions for gluing and attaching them but I don't want to risk it not working especially as they were a bit more expensive. I called Canadian Tire and they said they are fine to return, even if I've taken them from the package. I was honest and said they are not what I thought they were, plus they bubble up and don't lay flat and they said I could return them.
I just saw the same ones at superstore for $15 so I may get those and pull them out for special indoor play.