What you have been doing is good in terms of the process, but if you value your time, I think there are 2 ways to accomplish what you do and more, in very little time.
Nik SilverEfexPro v2 is a wonderful B&W conversion tool that not only enables fantastic control over how the image is converted to B&W, but also has control points that allow you to target specific local areas for individual adjustments. Masking gets done magically, and the results are stunning. In addition, you can treat the layer that is produced as a smart object, which then may be readjusted to your heart's content.
I also just downloaded and tried Topaz B&W Effects, much less expensive than the Nik software, and while different in concept, just as powerful. It also allows local adjustments with an adjustment brush much like the one in ACR in its ability to mask the areas you want to work on.
While both programs have a substantial learning curve in order to squeeze out all of their benefits, you can get a good start working fairly intuitively.