I'm selling my house and decided to help my real estate agent by providing 2 composite neighborhood highlight images.
Both were created from my personal images (minus the actual trail map) using Photo RAW layers transform tool. I tried using PSE (create a collage) 1st but found it was extremely difficult to control the spacing and size.
My agent loves them and said she'll be using them.
Your idea of providing composites is a good one because only you know what best to highlight about your property.
My only comment would be - personally - I need separation between the photos. The bottom composite is fine because of the color variations, but the top one jumbles together for me.
If you decide to do something to separate the top photos, I suggest you do the same technique for the bottom ones (even though it is not needed) because you would want consistency in your finished pages.
As far as using some third party way of doing composites -- like you, I find it easier to do it from scratch. Most times, photos just don't have a 'one size fits all' mode.