I stopped following Angel after the second season. I stopped following Buffy a little into the sixth, but I later saw it all in reruns. Now I’ve made my way through Angel season 3 on DVD, and I just finished season 4, disc 3. I’ve also been following the old Angel threads here. I like to pretend those last two seasons of Buffy didn’t happen, but I’m wondering if there are any crossovers that might make it worth watching some Buffy again. I do know that one certain character crosses over later on, and then that other, but that’s it. Is there anything else that’s really important, any major plot points?
IIRC all the crossing over happens from Angel to Buffy rather than vice versa, so you’ve seen all that there is to see. Enjoy the rest of Angel; it ends much more gracefully than Buffy did.
Um, I remember the opposite. Buffy characters–Willow, Spike, Andrew–“cross over” into Angel, but I can’t think of any examples of a vice versa.
(And FWIW, Buffy got better from season to season; S6 and S7 were the best television in history. Just so you know.)
The only Angel to Buffy crossover I remember after season five is when Angel shows up in the penultimate episode of S7. There’s no real reason to watch it though, since the effects it has on Season five of Angel are explained on Angel.
I don’t want to get sidetracked into a debate, so all I have to say is:
Magical crackhouse.
Magical acid trip.
Magical drunk-driving accident.
Yeah, but the Willow arc was stupid, whereas the Spike arc was magic. Lots of Buffy folks show up later on Angel. You really need to see what happens with Andrew, for example, to understand him when he guests at the end of Angel. But the biggest problem is with Spike. Without the last two seasons of Buffy, Season 5 of Angel makes no sense whatsoever.
I thought that the OP had actually seen all of Buffy. He just wants to know whether he needs to watch it again.
Obviously he didn’t watch them closely enough! 
Willow, Andrew, Spike, Faith, Buffy (kinda) all show up on Angel in Season 4 & 5.