What Do You Use For A Ground Cover?

I guess we'll need some sort of ground cover under our feet in the kitchen and under the EZ Up, so we're wondering what all of you use. I've seen some products that advertise the ability to let water and dirt drain right through, but they seem pricey.
What's the consensus here?
Cheers,
Debbie
What's the consensus here?

Cheers,
Debbie