Spend Halloween night at a swanky Westside soirée as 1,000 guests swoop in on the Viceroy Santa Monica. The boutique hotel has tapped Three Day Rule to deck out the entire property with haunted decor—i.e. dripping blood in the lobby, ew—drinks and DJs. Circulate between two dance floors and stick around for a prize-filled costume contest. Costumes are mandatory and though the party is open to everyone, it's particularly geared toward singles.