Interlocking rubber tiles, rectangles, brick patterns, etc. work out great. They are easy to install and maintain---if you damage one you just pull it out and slip another in its place. They are great over concrete since the flex and you don't have to glue them down in most cases. You can get all sorts of colors, thicknesses and patterns.
Shop online though for your best options. The limited selection box stores have are of poor quality and too thin to start.
Rubber floors are great to walk on and for kids and pets to roll around and play on.
The only real drawback? The surface is porous so make sure any construction material dust is past tense and cleaned up or you will grind it into the surface.