Even though Mt. Wilson is only 26 miles from you, topography is blocking a direct view of some of the transmitters there, making a few important stations much more difficult to see. LA is going to have 4 VHF digital stations after Feb 17, so having VHF reception will be very important to you. I'm sure that your metal roof has played havoc with your digital reception.
I would suggest using a Winegard HD7696P VHF-high-band + UHF antenna mounted on your roof, but at least 5 or more feet from the metal roof. Aim the antenna at 285 degrees from your location, and use high-quality RG-6 coaxial cable from the antenna to your TV converter: you should see all of the LA stations without much of a problem.
http://www.winegard.comhttp://www.pctinternational.com/channel ... lation.pdf