Can anyone comment on the appropriateness of the "Subscribe" button (PayPal Payments Standard service) for my website? I offer 3 subscription levels, and want to accept credit cards without requiring that my customers have a PayPal account.

Would this work? Is there a better way? I'm looking for easy copy-and-paste HTML integration, along with good online financial tracking and the ability to refund customers, etc.

It would work fine. It's quite simple to create the subscription button actually, go into your PayPal account and in the top menu click "Merchant Services". Find Buttons and click "Subscribe". This will allow you to custom the button and recieve the HTML code to place on your webpage.