I've bought/sold bikes on CL, BARF and Stromtrooper. You have to shop/lurk for while (possibly months or years) and get a feel for the market but be ready to pull the trigger at a moment's notice when you spot a deal. Bay Area prices are the highest but you can use CL to expand to surrounding areas if you are willing to do a fly-n-ride or drive-n-ride. I almost did a fly-n-ride to Reno but the price differential wasn't enough to justify the cost/hassle. If you can find a forum that is specialized in the sort of bike you want then I'd keep an eye on that forum's market. I have a theory that the best bikes never hit CL, they sell on the specialty forums to knowledgeable users or on popular general forums like BARF.
My current bike was found on Stromtrooper at a good price and just over the hills in Madera so I did a drive-n-ride to get it home. I wasn't even shopping for a bike at the time but this bike was exactly what I wanted, in the color I wanted, super low miles and with a lot of extras at a good price so I scrambled to get a bridge loan to close the deal then sold my old bike here all in about 2 weeks. Finally, better prices in the Bay Area are coming in Oct/Nov/Dec after that you can still get deals in Jan/Feb but generally sellers will hold till Spring to get the higher prices.