Start 1: A duke wants to find his son, missing for 20 years. (Unbenownst to the duke, the son has been changed into a werespider, and is hiding out in shame.) He gathers together a team of adventurers who don't know each other. But they have this in common: he has a hold over each one of them.
A different hold in each case. One of them, a thief, tried to rob him and was caught. He's not pressing charges... yet. The wizard is an apprentice of a man whose life the duke saved during their adventuring days; the master requires the apprentice to serve the duke as part of his education. One's the daughter of a family friend; one's the scion of a noble family that has fallen upon hard times, and taht the duke can help politically; and so on....
(Comic-book readers may recall the similar premise of a DC comic book called "The Secret Six.")
As they adventure, the characters get caught up in a conflict between the anicent spider goddess and the more recent goddess who replaced her. But they always had their primary mission - find the duke's son, or his fate - to give shape to their motivations.
Start 2: An isolated, little-known archipelago is opening up trade and cultural relations with the mainland. The powerful Church of Baldur on the mainland learns that their co-religionists on the archipelago - who, a century ago, were in a position of great political power - are now a decaying and decadent sect. They gather together a group of adventurers to be a "trade delegation," secretly tasked with learning the history of the Baldurans on the island. As the campaign continues, the party becomes, first, aware of, and second, involved in, the political struggles of the islands, and have to choose sides.
These both worked pretty well for me.
The Spectrum Rider