Foreigners with Chinese spouses trying to renew long L visas at PSB's other than those of their spouses' hometowns will run into trouble, in my experience.
I tried to do so once. But at first the clerk was only willing to give me a 10-day L visa! However, after my Chinese wife started a rather long quarrel in public there, he finally relented to some extent - I was issued with a 30-day L visa, but I suspect he was breaking the visa regulations. Not that I was complaining - 30 days is better than 10 days! I think that there's too much red tape in China, not just for foreigners, but for Chinese too!
By the way, it's worth pointing out that it's unlikely you can still get a long L visa from a Chinese visa office not on the mainland if you plan to enter to visit your Chinese spouse. You'll get a 30 day L visa, and be told to extend at your spouse's hometown's PSB office if you wish to stay in the country longer. That happened to me during the year of the Beijing Olympics. I believe it's still the case, though I have read that some rules re F visas and Z visas had been relaxed some time ago after the Olympics.