I agree with TJC, it is a shame that you are limiting this to Visa card members. It is great for small business travelers or those who have flexibility with payment. However, when you are employed by a large company and travel more than 50% of the time you are required to use certain corporate cards. That being the case it is almost always AMEX, I think you missed the mark on this by limiting it to VISA payments only.
Although I was told on the phone that I would automatically be registered as a Plat Elite in the September bonus, I just checked and it is not listed among my promotions. This is clearly much more complicated than the original post made it appear. (Though they still have a few more hours on the 11th to make it happen.)
I know that many companies require Amex; my college did till it got too expensive last year. Fortunately I already had a Premier Signature Marriott Rewards VISA card. For that, I cannot say enough. Basically I use it like a debit card and pay my balance off every month. Besides what I get from Marriott, I get 5 points per dollar spent at Marriotts, 2 points for all dining and airline purchases, and 1 point for everything else.
I want to assure you all I'm in no way associated with the VISA card (that'll be the day) but combined with a large number of European stays, I get about half of my stays in Europe for free.