I think if there were a dungeon design that took several weeks to get through it would keep player's attention and they would stay to build their template. The dungeon could be designed so as you go in the spawn is easy, like skeleton. Once you reach a certain skill level you are able to proceed. This way you would have to work up to a certain skill point before seeing what's next. It would be important to have good music and a real interesting type of interaction with the spawn. All the skills should be considered so that all groups could walk the same path. You should be able to roll out a sleeping bag and set up camp to log off so that you could stay inside the dungeon and not leave until you've reached the final level. There could be simple things to tame in the beginning. There could be treasure maps that could be found easily maybe by placing an X on the map as well as on the ground. Any kind of gear that is needed should be found on the loot, such as, reagants/lower reagant armour, bandages, arrows. All the skills should be considered starting in the first level, lockpicking, barding, so no matter what type of player you are creating you can find what you need to gain in skill and protect yourself, such as armour and weapons. As you get better there could be a storyline that runs alongside to document your achievements and help make the dungeon more interesting. There could be things that will change over time but not change the functionality of gaining skill and acquiring gear. Bosses could appear at the end that might take teamwork and they could offer skill gains and special gear that will help your journey along, including titles as long as a person carries a certain title they may be able to do more damage or be more proficient so that it would not just be a title. They could leave the dungeon around 80-90 skill with some pretty decent gear. They could be given the option to leave the dungeon and re-enter. It would be nice if this could be done where it could keep the player actively questing through the dungeon for about 1 month or X amount of hours. I think that would be the key in designing the dungeon. The time it takes and the intensity and addiction to finish. This of course is just an idea, hopefully they could create something where the hours would pass by and there could be a surprise around every corner. There is so much content in UO, if everything was used and placed into this dungeon it could be the greatest ride ever.