- Nik Vinter
Whenever you design something the page is your canvas. Go wild.
Except that sometimes it doesn't work like that. You can't just simply put seventy round rooms in a castle. Players will start asking what's going on, what was the purpose of those rooms? How have they been built?
Realism is a thin line.
Gygax himself said that every dungeon should have empty rooms; I'm pretty sure he didn't mean literally empty rooms but people still tend to do that. I had a similar experience in one of my games where my players entered a place that had nothing but some barrels and they spent 10 minutes arguing about what purpose that room served. Too many random rooms and your players will find themselves alienated, too much realism and your players will be bored. There's a reason we play fantasy and not reality. Reality is mostly boring.
And there's a delicate balance in between. I love putting fuck a diddles in my dungeon. They're fun for me and for the players, it transforms the dungeon in a bag of chips as once you open a door you alyways want to find out what's in the next. I think the best way of describing my works is "Theme-Park Dungeons" (not sure if I'm the first one to use such an expression), but I always have to be sure to leave a general thread an theme in the background. Too much weird rooms and the players will have no means of predicting and reacting to the environment.
Some people use real maps of places to draw inspiration for dungeons, that's also an awesome idea because it simulates the realism of a real world place leaving enough "knowledge" for players to grasp to. Dungeons don't have to be only beautiful but actually functional (Yes I'm looking at you "Dungeon Of The Blue Medusa") unless you're specifically going for that "weird" aesthetic.
Once you have a solid basis then you can start going wild (with moderation). If you don't have that it's important to mantain a level of realism in the rooms as well. From my experience I think roughly 60% of the rooms should have an explanation of "why is that thing here". Be sure not to overdo it, this will remove any magic of exploration from the dungeon.