A few months ago we were gifted with lots of mats.... lots.... like 24 squares of the stuff. It has been so much fun to roll over, jump on, or make snap together forts with these squares. We decided they would make a soft, durable base for a car mat.
For the little buildings, we cut apart one Kleenex box and flipped it on edge. For the tall tower building we taped a square of cardboard together and drew windows and doors on the surface. It seems overly simple, but young children like to use their imagination and also move objects around. If you draw everything in place, it's just not as exciting as when you can move them around on a mat.
We had a store bought fabric/carpet mat once, but the kids wouldn't play with it very long. I think it was to busy, to many colors and designs so that they couldn't easily see the roads. We made this one easy on the eyes for tracking abilities.
More of something is not always better. Neither is having to many of one thing. It makes children overwhelmed and parents upset with their lack of ability to keep track of it all.
We have heard and read from a multitude of other parents that simplifying and getting rid of excess toys and playthings is a great benefit. Use more time to create and make things with your children. It makes for good memories, will help you overcome your perfectionist tendencies and they will learn to take better care of something that they have invested time and energy into.
PS As parents, the more time and energy we invest into our children's lives, the better care we take of them as well. Who'd of thought play time was so important? It's not about having all the latest toys, it's about spending one on one time, giving them our full attention, and looking into their eyes, enjoying their presence with us that matters.