I thought about it for my gym space but read that the rubber smell lingers for a significant amount of time after installation.

Look into Roppe rubber flooring. Incredibly durable and goes down like big vinyl tiles with mastic. We used the raised dot design in a contemporary kitchen. Follow this link... http://www.roppe.com/products/raiseddesign/index.html

Rubber smell is going to be the biggest draw back. For asthmatics, this can be a big, big problem. An incredibly durable floor - without the problems with smell - is a cork-rubber flooring. Sadly, my company does not produce them, but they will give you MOST of the benefits of rubber without it's draw backs. The issue with rubber and cork-rubber flooring? $$$$$$$$$ Big money for these floors because they are usually considered commercial/industrial grade flooring and have a large cost to them. Depending on the make, they may have special installation instructions and "nasty" adhesives that go with it...again, these are mostly used for commercial/industrial spaces - same as rubber.

Do a web search for "cork-rubber" flooring and you will find a small, but interesting variety out there.

I suggest you look at www.softnsafefloors.com

You might also look at a physical education catalog online. Wrestling mats are easy to wipe clean.