I head in an opposite way. For my table, long dungeon crawls for the sake of a dungeon crawl isn't an interest. I usually plan out my dungeons using the Five Room Dungeon method (google for more then you ever wanted to know). It doesn't refer to five actual rooms, just five main points of interest:

Room 1: Entrance And Guardian
Room 2: Puzzle Or Roleplaying Challenge
Room 3: Red Herring
Room 4: Climax, Big Battle Or Conflict
Room 5: Plot Twist

Now, onto that I'll add in additional points of interest for plots and campaign arcs, including laying foundation for ones that characters aren't aware of and points that would make sense for other campaign arcs then than what the PCs think they are doing at the exact moment. "Onto" could refer to more locations, or overlaying them on these locations. If the primary foes are summoned demons all wearing a fine iron chain inscribed with tiny ruins, that's an easy link into one plot and should make them wonder why that diabolical patron is involved, etc.

I like color for color's sake, but I also don't want to draw out a dungeon for too long. I'd much rather gloss over "searching and finding several empty rooms - bedchambers and the like, covered with undisturbed dust and long-ago ransacked" then to map out going through each of those rooms and making each on have enough details that we spend 10-15 minutes each and eat up an hour of the 3 hours every other week we play without having gotten advanced the plot. An hour of play is about the equivalent of five days of waiting for the next session - I want to make it count.

That said, there are plenty of quickly resolved tools I can use to make a big complex feel, well, big. My #1 tool, taken from 13th Age, is the montage. Once the players have the feel, I'll do a montage scene of exploration, with each player contributing a minor challenge or puzzle and how they overcame the last one.

Another I use are challenges, which in some ways are free-form descendants of skill challenges but without the formal "X successes before Y failures", also allowing use of resources (spell slots, consumables, knowledge, etc.). I might also use a montage to show how successful (or not) they are.

Let me give an example of that while combining with not taking the rooms literally. In one "dungeon" the Entrance and Guardian "room" for a Ice Castle made by a Vampiric Frost Giant Ice Sorceress was how to find the throne room they knew they were heading for while avoiding ice-based traps and Frost Giant Zombies. But in a more abstract way, not as a series of encounters, sicne ay particular trap or small group (heh) of Frost Giant Zombies was too low a level to kill them.

So we set up about the rogue taking point, how to efficiently deal with the Frost Giant Zombies (once they discovered they weren't an on-level combat challenge), spells, methods and skills used to make as direct a bee-line to the throne room in the purposefully confusing castle to minimize the traps and frost giant zombie encounters - then it went to a montage of dealing with them based on it, including damage and resources used, to get to the throne room. Took 20-30 minutes total.

ncG1vNJzZmivp6x7prrWqKmlnF6kv6h706GpnpmUqHyjwcilm6Kml2K2r8DEq5ysrJmjtG6w1KeenqeeYr%2Bwu8ysZW9tZGqDc3s%3D