110 episodes of ANGEL aired from 5 October 1999 to 19 May 2004.
Angel Episodes with Sarah Michelle Gellar
I Will Remember You (1999)
Sanctuary (2000) Soul Purpose (2004) (only back of head visible. archive audio)
Archive footage of Buffy used in the pilot and 4 other episodes:
City of (1999)
The Bachelor Party (1999)
Just Rewards (2003)
STEPHANIE COURTNEY, the Progressive Insurance chick, was Gwen, Files & Records in the Angel episode "Dad".
Eleven characters (other than Buffy and Angel) crossed over to ANGEL from BTVS for at least one episode. They are: Andrew Wells, Anne Steele, Cordeila Chase, Darla, Druscilla Keeble, Faith Lehane, Harmony Kendall, Daniel 'Oz' Ozborne, William 'Spike' Pratt, Wesley Wyndham Price, and Willow Rosenberg.
Gellar's participation in the Angel series was really limited to two episodes, both in Season One. In "Sanctuary", she comes to LA chasing after the fugitive Faith, only to come into conflict with Angel over how to deal with said fugitive. Then, in "I Will Remember You", she returns to give fans closure on the relationship (Bangel get to be a normal couple for a day or so).
The relationship bears similarity to that of Diane Chambers and Sam Malone. Think about it. They have nothing in common, always overthink everything, and every time they threaten to be happy something disastrous happens. True, Angel is a bit more literal about being a lady killer, and his guilt trip is much more intense, but the fundamentals of the relationship are the same. They are together because they want to be alone, Diane in her chambers, and Sam alone.
After Season One, Angel the Series never saw Buffy again, except via archive footage. The differences between the Angel series and Buffy the Vampire Slayer then became apparent. Once Kate Lockley (Elisabeth Röhm) the friendly blonde cop left the show, there was no longer anything to anchor the scenario in reality. It was like Angel and his buddies holed up in an abandoned hotel and dropped some bad acid.
Angel subtexts were disturbing to say the least. Lawyers are evil; vigilantism is good; the end justifies the means. BTVS never suffered from this sort of libertarian excess.
The two really good things about this series were Amy Acker (whose character may have been entirely an hallucination), and Lorne, the gay green demon (Andy Hallett). Especially interesting was Lorne's home "dimension" which looked not a bit like hell, and instead reminded one of 14th Century Europe with two suns. Angel's car, a 1968 Plymouth Fury, was also one of the better things in the show.