Worldbuilding - How Far Away is the Horizon?

  In both my Blackstone and Patchwork Lands campaigns I made worlds larger than Earth. In the case of the Patchwork Lands the planet is much larger - the diameter of the planet is 16,000 miles, a hair over twice the diameter of Earth.
  Since it is a fantasy world there is a lot of handwaving about gravity, etc. because I am more interested in vastness than the speed of a falling object (plus, there are reasons the gravity is still about 1G). But there is a question-
  How far away is the horizon?

  Here is a math formula
   Square root of[D x H/C]
  D = diameter of planet in miles
  H = height above surface in feet
  C = 5280

  So, on Earth a 6' tall person looking out across the plains would see the horizon as 3 miles away. From the top of a 30' tower (36' total!) the horizon would appear 7 1/3rd miles away.

  But on the world of the Patchwork Lands a 6' tall person would perceive the horizon as being 4 1/4th miles away and from a 30' tower that same person would perceive the horizon as about 10 1/2 miles away.

  Now, I am just eyeballing it here, but this appears to mean the horizon is about 50% "further away" on my new world. This also means things like mountain ranges in the distance can be seen a long way away.
 Here is an example: I created a 7 miles high mountain in my world. Because of the larger diameter the peak should be visible from someone standing at sea level 334 miles away. To put that in perspective, on a clear day if you stand at the summit of Dankova mountain in Kyrgyzstan you can just see the tip of the peak by the Hindutash Pass: this is the longest ground-based line of sight on earth and it is... 334 miles away.
  This was completely coincidental, by the way.
  But ti does mean that from the largest mountain in my main story area someone standing on its summit could peer across the plains between and see that peak clearly because the distance between them is only 500 miles!

  It is always the little things in worldbuilding that surprise me.