M.M.
I LOVE LOVE LOVE my gate from Retract A Gate.
It's the only one I've ever found that doesn't become a permanent eye sore. Bonus - the kids can't climb it! And I can verify from years of person use that it works 100% - even when they come charging into it with full force!
You fix it to the wall, and then it can roll up when you don't want to have it up.
http://www.retract-a-gate.com/