Here's the things I generally rely on:
1. Every location has its own story. The layout of the dungeon tells that story. What is the story of this dungeon? Well, there's a river that runs through it. Okay, what does that river do? Does it affect what sorts of enemies are there? Flora in the area? Did the water carve out the dungeon in a particular way? Where does the water come from? Where is it going? Etcetera.
2. Each "room" needs a theme. This room has a bunch of skeletons in it. Why? What's the theme? Death? Danger? Grief? Is the next room a graveyard as a result? Or a half destroyed cathedral? Etctera.
3. Each "dungeon" needs a purpose. What is the reason the player needs to enter this dungeon? If your answer is "gain levels", then your dungeon doesn't need to exist. If your answer is "because RPG's have dungeons", then your dungeon also doesn't need to exist.
Here's two examples I'll give you from my own game:
Poison Dungeon
The purpose of this dungeon is to introduce several mechanics to the player. It is meant to introduce how a dungeon will work (namely, if half your resources are gone before you hit the boss, you need to leave and come back with more). It is meant to introduce how Poison works (I have a Level 1 and Level 2 variant at play in this dungeon). It is meant to teach the player basic mechanics bosses will use (the "Revenge" mechanic in particular, but there are other things the enemies will throw at the player they need to learn). It is also meant to teach "basic weaknesses" to some of the specific enemy archetypes. It is a training dungeon.
Lover's Leap
This dungeon serves two purposes. The first is it delivers storyline between two of the main characters and helps resolve a few things early (or at least, begins the journey to that resolution). The second is that it is meant to teach the player about "Priority targets". Or, rather, how to better economize your actions. You have a "warrior" class with a "mage" class. The player will be pitted up against enemies weak to either type, both types, or maybe only conditionally weak to types. It is to showcase "working together" to win. It also showcases the "Silence" type skills that can lock down EITHER of the party members.
4. Dungeons need "character". That is, some of the "character" of your dungeon is in what enemies reside there. Or, even, what mechanics the dungeon employs. Do all the enemies in this dungeon cast Confusion? That adds to the character of the dungeon. Are all the enemies types of dinosaurs? Well, that adds to the character of the dungeon as well. Likewise, try to add "layers" to a dungeon as well. If you can have steps going up or down, or ledges sticking out of the wall you can't get to, it adds to the "character" of the dungeon as well and breaks up the sightlines a little. Or, rather, it breaks up the monotony of a single tile type repeating.
5. Good "loot". If all you have in your dungeon is consumables and money and maybe equipment that isn't useful at all... What does that add to the dungeon in terms of memorability? But, if this is the dungeon where you fiddled with a switch, found a secret door, and now you have a sword that can instantly petrify enemies and cause them to die... Well now, that makes the dungeon interesting. Are there other secrets here? Other cool pieces of equipment to gather? What if the player got a new piece of equipment for each character in here? Either a weapon or a piece of armor?
6. Interesting map layout. Walking in straight lines is generally "not interactive" enough. A player that has to go around several corners is more likely to enjoy the dungeon more than one who just runs straight lines. Especially if the maps "interconnect" to each other so that an internal map can be drawn that allows the player to view how it all fits in their head.
