Even if you seal grout for the tile, it can stain and absorb some smells and stains. If you go with tile, you may want to use an epoxy grout...it'll cost more, but is pretty impervious. A skirted toilet will be easier to keep clean. A very important thing that may not have been done on your toilet is to caulk around the base of the toilet to prevent anything from seeping underneath it. You can clean as much as you want, but if it's underneath, after awhile, it will smell. You might ask them to sit while urinating...less chance of it going everywhere, but no guarantees!