Choosing between reguler tile or glass tile for a spa which is easier to clean and more durable?

Glass tile is more expensive than ceramic or porcelain. Glass scratches easier and the others. During installation, you use grout that does not contain sand because the sand scratches the glass during installation. If you are using it in a spa, the sanded grout is a nice added measure of safety that you wouldn't have with glass. It can also be a bit trickier to install because you can sometimes see through the installed tile to the wall and adhesive behind the tile.

Glass is very beautiful when installed correctly and in the proper application.