If by chance you have or are planning to get Presonus Studio One, there is a built in mastering suite included in the higher version(s), which many swear by as well.
EDIT: Forgot to mention that with Studio One's mastering, one of the options that's really cool, is that if you go back and make some changes to any songs, those changes are automatically updated in those songs that are sitting in the mastering suite - a huge time saver.
So although I don't use Studio One much, I will be trying that first when the time comes to master, as I already have that DAW installed.