Spaying is not only good for the health of the dog, (overian (sp?) cancer and cancer of the mammory glands (nipples) are far more common in un-spayed bitches. But it will save you lots of mess: bitches in heat will bleed, and chances are they will "scoot" and get blood on everything. You must keep panties on her while she's in heat. It's also good for your sanity: bitches in heat will "draw a croud" and by that I mean they will attract every male dog in a huge range(both neutered and intact) and you will have to be chasing off males who want to meet your female.

I am sure you are aware of the horrible over population situation and it's because of unresponsible breeders/owners who are hugely at fault.

Spaying is the way to go. It's a quick surgery, but the benefits are endless.