Understand you will NOT find all comparable luxury listings on Trulia, only the MLS. There are several aggregators of luxury homes such as http://www.LuxuryPortfolio.com and many franchises have their own luxury web presence however the only place they all come together is on the MLS.
If I can be of assistance...
It appears that 270 Beach Road, is being shown by appointment only. Sometimes sellers in the luxury market choose not to hold open houses. If you contact me directly, I'd be happy to arrange a private showing for you. Also, if you'd like to search for other homes in the Tiburon/Belvedere area you can do so from my website listed below.
Warm Regards, Leslie
McGuire Real Estate