Yes Brian, I bought the 4 inch one because it is best for my 8x10 and 12x20, since you got your new toy I guess you will be using 8x10, and I would recommend the 4 inch one. If you plan to do smaller then the 2 inch is best for 4x5 and 5x7.
Jeremy, in my experience evident brush strokes are a sign of low humidity, when I have low humidity even with two coats I get crappy brush strokes. I ruined 2 12x20s like this. If you are seeing this too often then perhaps running the paper a little over steam will help you. I hope Joe or Clay chime in, I am not really that expereinced, I am lucky that I found a way that works for me and I stick to it.