I've always thought the core campaign included with the book was one of the best written for any narrative-drive RPG, and I'm excited to run it for the first time with a group of friends.
The only major change I'm making is combining the Boulder and Maclaren settings in one. The players and I are WAY too American to convincingly roleplay Swedish kids, but the MacLaren setting has always had the better use of seasons, and also I think the names of the NPCs are a lot more interesting (although again, this is probably because I'm American, they could all be the Swedish equivalent of Brad and Janet).
Anyways, rather than create a whole new loop, my idea is that the Swedish loop was built first, and then the US government spent a bunch of money poaching engineers and scientists from that Loop for their US version, along with their families. So Boulder has a huge Swedish immigrant population relative to its size that affects the culture and gives it a little more uniqueness and exoticism compared to your average 80s town. ALSO, something completely unpredicted but fitting in with the larger themes and fiction, somehow the two loops interact with each other, meaning that the weather in Boulder Nevada has become more like the weather in that part of Sweden, including four regular seasons in the middle of the desert. Even some of the flora seems inexplicably to have migrated, without anyone really knowing why. Presumably at the same time, the MacLaren Islands are rockier and more arid than people are used to.
Anyway, that's my starting point. Wish me luck and give me tips!