Here's a consideration:
Depending on the height of your stand, and whether or not you'll use a canopy, the 24" tall setup may be a real PITA to clean without a small "kitchen" step ladder. IME/IMHO, the 18" setup would be plenty tall (use about 1" - 1.5" of substrate), easier to maintain, and will give the SH more lateral room.
I do recommend going with a RR + sump or AIO type setup with a CL (since you're having the tank built).
As for "colorful SH", as you research more (kudos for that BTW), you'll learn that SH can be pretty much any color they darned well please, so don't pay extra for it. H. reidi tend to be a bit more colorful than H. erectus, but if you're planning on rearing fry, you might want to go with erectus because their fry are much easier to raise, but still not simple by any means.
Make sure you get TRUE CB SH from a reputable breeder or hobbyist/breeder such as Seahorse Source or Peka's Ponies.