You may want to consider the Pasadena Museum of Contemporary Art. Their webpage is not very helpful regarding planning your wedding there but I've officiate a few weddings on the roof and it is a nice venue.
490 E Union St Pasadena, CA 91101 Neighborhood: Pasadena
I agree, the Pasadena Museum of Contemporary Art is a great location. I played a wedding there last year. They have two areas on the roof. One inside and one out. For the wedding I did we played the cocktail hour outside and the dinner/dance inside. Happy hunting and congratulations, Gerry Rothschild The Gerry Rothschild Band "We've Got Your Music" www.grbands.com 626.791.5305