Then I don't think Cordy should've went on that vacation. This just irks me now.Actually, it is right for Xander to be unincluded on the Chase family vacation. He and Cordelia didn't actually kiss for the first time until What's My Line which was halfway through the season. She didn't fully acknowledge and accept him as her boyfriend until a few episodes after that at which point the show is gearing up towards the finale with Passion.
Xander would've only been officially acknowledged as Cordy's boyfriend for a few months at most. We don't even know if he met her parents and vice versa. There's no way he could afford to go on the trip and there is no way that Cordy's parents would pay for him to go.