Nicely done, if you want to really get into the GND filters for sunset/sunrise than you need a reverse GND filter and they can get costly. What they are is the darkest part of the filter is in the middle and gets lighter as it reaches the top, I use a 3-stop make by Singh-Ray.
Link to Singh-Ray provided
http://www.singh-ray.com/reversegrads.html
Until you decide that you are going that route, I would do it in myself in PP (ACR) using the gradient tool as long has I have not blown any highlights PP will do a pretty good job.
Cheers: Allan