Since making this thread, I've compiled a few details from several playthroughs:
-> Your tour will be with Thomas or David. The end result is the same, but if you go back and wait for David the second time you're prompted on the Thomas tour, Norman will join in to greet you in your room.
-> Most days you have the choice of going in early (Norman Route?) or waiting to go with Thomas (Thomas' Route). You'll usually be offered the choice to go to dinner with Thomas, too. Not going doesn't make a difference except you lose some Thomas points.
-> Thomas' route is "easy mode" in that he's always easy to locate and spend time with. He will confess love to you on the final day if you gathered enough points with him. You can still screw it up, though--be too sympathetic to Charlie (who he doesn't like), or take the "spanking" prank too far, and he will get upset with you and you may end up closing off the route.
-> Kevin has a minor route, but it's tricky. You have to meet him every time he's available and you have to pick the right choices. Kevin is gruff, and his choices tend to be split into "bold" or "retreat", but he responds best if you pick the retreat options and avoid him. He's dressing in the locker room on the evening of Day 5 (Friday), and day 6 will offer you the chance to watch him and his girlfriend argue. If, both times, you avoided confronting him, he'll be available to help you with the truck on the same afternoon IF (and only if) you ask Thomas to help you first, then choose Kevin when prompted since Thomas recommends someone else's help. Find him again and respond submissively on Day 8 when he's in the bathroom, and on Day 10, you can find him in the shower, where he'll confront you. When he asks you why you avoid him, if you say "you're cold", you'll close off the route and continue as normal. If you say "I don't know", the game will skip to a camping trip on Day 15, where you'll room with Kevin and can press him to tell you why he's cold to you, which he responds to with a kiss. This closes off the route (and the game ends) for now. There are other scenes with Kevin, but if you're seeing them, your chance to get this scene has passed.
-> Successfully fixing the truck with Kevin's help will open up some other non-Base areas to explore on certain select days. There are other people to meet out here, but I've yet to be able to meet up with any of them more than once.
-> Norman and David seem to have routes, but I haven't found that paying them special attention leads anywhere.
-> IMPORTANT: The game will skip days or weeks at a time depending on how you're doing. Days 6-8 will repeat until you appear to have chosen a route to pursue. You can skip to Day 10 after Day 6 if the game deems you have chosen Thomas' route that early. Performing Kevin's route correctly will skip you to Day 15 after Day 10. After reaching Day 13, the game will skip ahead to Day 21 (Thomas Route) or 29 (after Thomas Route Day 22 or no route chosen) and the game will end there.
Corrections and additions are welcome!