The Beauty of Bastards - Sandboxes to Burn

Two of my campaigns are founded upon a single commandment - get rich or die trying. This had led to both games being the chronicles of a team of utter bastards wreaking merry havoc across the land (see the early LotFP write-ups for the origin of the Six Bastards), and I honestly find it to be the most satisfying thing to DM. The principle motivator of money explains the group sticking together, and lets you realistically plan what they're going to do. What with this being a role-playing game, things are guaranteed to get interesting when the characters are choosing between riches and non-monetary gains.

The mindset of trying to take the world for a ride also means the players are going to examine everything for potential gain, both within dungeons and within settlements, leading to some fun world building and some excellent (and not so excellent) plans, including dungeoneering for political funding, organised smear campaigns against noble houses and the blackmail of armed forces. A well-thought out sandbox with interesting scenarios for the players to get embedded in works wonderfully, especially when they cause things to backfire on themselves.

The only potential issue is ensuring players aren't too eager to betray each other - so far, it's mostly been the shared knowledge of atrocities and honour amongst thieves. Running LotFP, alignment isn't an issue for this sort of play.