Please forgive me if the answer is well known, but I am new to SPG world.

We use AA frequent flyer program and have been using a Citi-AA Mastercard to pick up miles from routine spending. We are now considering switching to a SPG card because of their generous 25% bonus when converting to miles. (Of course, while this is motivated by AA miles initially, once we get addicted to SPG points, we would tend to gravitate towards their hotels too. )

However, is Amex the only SPG card available in the USA? This is a concern as my impression is that it is accepted in fewer places than MC/Visa.

A casual check at spg.com as well as Google did not reveal any MC/V for US customers, only in Canada.