I think this is it.
Two Roads Diverged in a Wood by Darkrivertempest
http://spikeluver.com/SpuffyRealm/viewstory.php?sid=27855&warning=NC-17Summary: AU. Totally human fic. Willow, Xander, Buffy, and Spike head on vacation in the wilds of upstate California where the rain, boating mishaps, and the local beasties make the trip a living...well, you get the idea. A very light-hearted poke at summer vacations.
***WINNER of Judge's Choice Award Round 4 at the Spark and Burn Awards!***
***WINNER of the Whipped Cream Award Round 8 at the Forbidden Awards!***