Do you use pre-published adventures or do you write your own?Pre-published adventures really do have a great place in the gaming community: they provide new GMs with a great way to provide a complete, self-contained storyline complete with everything necessary to run the game. Moreso, they provide GMs with limited preparation time an easy way to provide a quality adventure. For a long time, there was a prevailing opinion in the games industry that "adventures don't sell". If nothing else, Paizo's numerous Pathfinder campaign paths have proven that perspective incorrect; well-written, well-paced adventures can sell like hotcakes.
For the most part, though, I try to write my own adventures, whether that's a full write up--usually for my convention games or for items I intend to publish--or an ad-hoc, ad-libbed adventure. My current Planescape game is mostly done ad-hoc, though I do have an overall outline structure for the campaign. And, truly, I find that my ability to GM extemporaneously allows players a greater amount of freedom, which most players like.
And The Last Sons is even bigger!
However, I'm not averse to using pre-published adventures: I had a blast running my group through the Deadlands plot-point campaign, The Flood, which took us about 10 months (meeting near weekly and playing for about 4-5 hours per session). While I used the bulk of the structure of The Flood, our group's playthrough included several diversions all over the Great Maze. The same thing happened when I ran Robert Schwalb's "Tear of Ioun" series for 4e D&D. While we used the fundamental structure of these adventures, we also weren't afraid to go off the rails. Our "Tear of Ioun" resulted in an aberrant siege the players' dwarven fortress, a confrontation against an undead barbarian, and a climactic battle against a Cthulhoid horror at the top of a ruined, crumbling tower--none of which was in the adventure series itself!
At the very least, think of pre-published adventures as a mine for ideas. Even if you're not using the adventure as it stands, any great adventure is full of maps, NPCs, and great plot hooks. Go do some mining!