There are other threads for this that you can look up in Fic Recs, just as an informative aside. And I'm pretty sure Elysian Fields has a section for that in their categories. So there's two places to look.
You've probably read all the ones I can rec, but I'll mention mine,
The Song Remains the Same, which is still a very long WIP right now. Sorry, but I'm ill and it's hard to write more than these little blurbs and reviews right now. <<sad horns>>
Another one I don't see rec'd very often though and that I really liked is
Falling Into Step By spikeaholic101 (Amarra17)http://www.fanfiction.net/s/2037130/1/Falling_Into_StepSummary: Buffy is a senior in high school and has recently broken up with her boyfriend, Angel, who moved to LA. Spike is the guy she can't stand...right? AU. WIP
And one I have that is not online anymore but I can send to you is
Changes by Stephanie459Summary: Buffy Summers used to be the fat girl, Spike Giles used to be the bully... What happens when one has a physical change and the other a personality change? The pair try and fight their growing attraction with blind hatred but what happens when pretending gets to hard...