There is no need to reinvent the wheel, Bitcoin has already done that. All we need to do is make spending bitcoin as easy as credit/debit cards. This can be achieved simply by a trusted third party system that processes customer to merchant payments. It would function identically to modern credit card terminal purchases.

Because no service like this currently exists, there is no monopoly holding back competition. This is where it opens up for aspiring bitcoin entrepreneurs. Any POS payment processing company introduced would be smart to provide a safe professional service or risk being replaced by a competitor.

Ideas involving sending the merchant more than the purchase and requiring them to send the "change" back or having multiple addresses with variable amounts to send are just awful. Let's keep making things simpler not take 10 steps in the wrong direction.