pricetack_pb - 7:45 pm on Jun 16, 2011 (gmt 0)
PayPal is still going to give you an edge over Google Checkout (in most cases) since it is still substantially more widely used (although certainly has its detractors).
You should definitely try to capture in as little time as possible (ideally 3 days or less). Different cards have different authorization periods and few are 30 days. Most debit cards, in fact, have only a 3 day authorization period. But as others have stated you will typically still be able to capture outside the authorization period with Google, PayPal and other gateways. But there is risk of the capture failing.