Hostage? O.k., maybe not. But I can't figure out a decent reason why Rachel would choose to date Hayden aka Darth........Actress Rachel Bilson and boyfriend Hayden Christensen checked into Casa Casuarina on Thursday night. According to our snitch, ''They had a romantic night that was planned by Bilson, where the couple stayed in the mansion's $4,000-a-night Safari suite.'' Our spy saw the couple check out early Friday morning. Later that day Blake Lively, star of CW hit show Gossip Girl checked in. Lively was in town for the weekend to shoot the cover of Teen Vogue.
