I'm read It's Dangerous Business, and while it was pretty good, there were a number of awkward moments in the writing and story. I am currently reading Lost and Found, and have found it really good except for Celestia's portrayal. (Her reasons and actions don't make much logical sense.)
I haven't read any of the ones you've mentioned in this post, though. (I've been meaning to re-visit Heart of Gold someday.)
How about This Platinum Crown and The Powers of Harmony? Both are really good stories, in my opinion. Have they just been around for so long that everyone glazes over them, or did a lot of people avoid reading them because the descriptions kept them away?