A giant Dungeon Crawl wouldnt be for my group but I can think of some things that might make it more interesting:
Take a page from Sunless Citadel, in which a tribe of goblins and a tribe of kobolds were competing for the same territory, and make the dungeon home to two competing societies (not necceasrilly those two). Either of them might be willing to work with the PCs in exchange for their aid against their rivals - depending on the PCs actions. A little bit of role playing can really help break up a big 'crawl.
If this is a really large and virtually unexplored dungeon the PCs may not be the only ones interested in it. Think about a boom town from the gold rush days of the american west. Hastily thrown together houses and stores, and mostly bars, casinos, and brothels. In this sitch it would also have magic item crafters, itenerant clerics, and magical "banks" to store loot in Strong Boxes of Holding or the like. Lots of interesting NPCs to ineract with, rivals to face off in the dungeon, etc. A little bit of role playing can really help break up a big 'crawl.
Portions of the dungeon are temporally out of phase with the rest of the Material Plane due to the experiments of the original owner. Occasionally the PCs trigger something that sends them back to whent he dungeon was a well inhabited lair of a cabal of wizards, allowing them access to areas that have collapsed and a chance to learn things they might not otherwise about what the dungeon holds, who built it and why, and how to defeat guardians left for a long time. A little bit of role playing can really help break up a big 'crawl.
Have intelligent magic items, comic relief mosterous humanoids, spirits that inhabit random party members to chide or direct the party in cryptic phrases, etc A little bit of role playing can really help break up a big 'crawl.
I detect a pattern. Basically, Dungeon Crawls are fine but if all the PCs do is check for traps, open the door, kill the monster/figure out the puzzel, go to the next door it will get realy really boring over 10 long sessions.