The first one, Spike is a semi member of the Scoobies, and he escorts Buffy to Hawaii on vacation ( I think it is council payed) since everyone else was busy for the summer and couldn't go and Buffy didn't want to go by herself. They have to share a hotel room, and at first they are barely putting up with each other, then the tentative friendship. There's something about Buffy wearing a super skimpy silver bikini which starts WW3. Also, unbeknown to them, the council sent people to watch over them, a man and a female. The female is I believe a witch, and has a mythical demon chase them through the forest. The demon resembeled something like a wild boar and it had a necklace or a ring in its nose, that turned colors depending on whether it was on a mission to kill and if the prey was dead (something along those lines). The man she was with ends up defecting toward Spikes and Buffy's side and helps them. I think at the end of the story Xander ends up going through the vacation photos and finds pics of Buffy and Spike naked in the hotel room.
The second one is set after the series ended. Buffy and Dawn go to Hawaii to relax and recoup after the battle and their losses. And they are in a little bungalow they rented. There's a legend but I forget what it is, but it does pertain to the story. Buffy breaks down in tears one night and her tears either land on the floor (which I think is magical) or on a statue. Not long after (maybe a day or 2) Spike is brought back to her and Dawn. There's more to it, but it's been a while since I read it that I might start to confuse it's details with another resurrected Spike story.
TIA | 
