I have those on my walls for protection against dings, marks and handprints lol. I bought two sets and have them 2 high all around the playroom with just a few spaces (I don't bother putting them behind the big shelves and kitchen set because they block the wall anyways). I think I got them on sale for $20 though. They will sometimes take the letters out but I just tell them that they are for the wall and we don't touch them. I have lost a few pieces in the beginning while I was still teaching them that we don't touch them haha. They are super easy to wash down. I have them taped to the wall with green painters tape and I have the letters taped on too now.

I bought a few packs of the 4 large mats. I have 12 of those (4x3) in one area of the floor for softer play and than the rest of the area is just the carpet. They are also super easy to wash with either a wet cloth or a wet swiffer.