I didn't get quite as far on scenery as I wanted this weekend, but I was able to get all of the cracks and rough areas along the seams of the stacked foam layers filled in and smoothed out using Mike Confalone's "Universal Mud" technique as described in his scenery videos. Out of respect for Mike's work, I don't want to give away his technique here. Instead, I'll point you to where you can purchase his videos and learn how he does it yourself. He does discuss his techniques in great detail and I've found his videos to be worth their weight in gold.
I was also able to run through three full operating sessions on Sunday and I found a few more rough areas in the trackwork I needed to fix before I finish ballasting the layout. Good thing I discovered these rough spots now instead of later.