Every mission that characters go on in my world can lead to more missions as some pieces fall into place. Do they receive rewards? Yes many can attest to that. As they get up in level they get better weapons and armor either by purchase or finding treasure. But in the same token all adventures are dangerous and can lead to a death or two. Experience is not given lightly as every decision can lead to fame and fortune or to death.
Players should be rewarded on multiple levels.
Physical, Mental, even Spiritual should you use those in your game.
One area that seems to be neglected in the majority of games is the Social Rewards. I utilize things like Fame and Reputation.
In the end, players need to feel like they are investing not only in themselves but also in the world around them. This can be done through Intrigue and Conflict and many other means, but the investment of a player in your world is vital.
While gold, treasure, magical items, and experience are all good ways to reward players in moderation I would much rather reward those that make good choices with more opportunity.
Much like the idea offered before of fame and infamy, or reputation, in that as adventures go about their journey doors may open and close based on their choices, decisions, and behavior.
Which is why being a murder hobo will never be something rewarded in any of my campaigns, as if the party's first answer is to always attack and kill everything they face… heroic intentions or status can be questioned.