In Downingtown PA they have an annual pond tour (for charity). It is mainly sponsored by a company who installs and maintains ponds. There are usually 50 to 70 ponds on the tour. For $30 you get a map of where the ponds are located and their addresses. You can go in any order to the ponds and of course you do not have to go to all of them, which would really be a challenge. When we go we usually get to only 15 of them. But the ponds are almost all fantastic. You get all sorts of ideas about ponds and see tons of great looking fish and flowers and plants and rock gardens and filters and water falls and streams with an without small pools in the streams. Some have bridges and some have walking stones across the pond. The owners are mostly more than willing to explain how their filters and pumping systems work. The sponsoring company has a banquet with beer and such at the end of the day. Food is great.
A similar pond tour was held by the West Virginia Koi Club in Charleston. When we lived there, my pond was on the tour. There were probably 20 or 25 ponds on the tour, spread over a wide area, but you could get to all the ponds in one day. Might be easier now days with GPS.
I use to belong to Mid Atlantic Koi Club. I do not remember that club having pond tours. But meetings were held at the ponds of members so we got to see a number of great high tech Koi ponds. They did have Koi shows with the canvas ponds of about 1000 gallons and high value Koi, and a lot of lower cost Koi.
One thing does stand out: ponds with high water flow to water features tend to have healthy fish and have great water quality.