As a San Diegan, I grew up seeing several bear species & subspecies at the San Diego Zoo... I seem to remember Manchurian, Syrian, and Alaska Peninsula brown bears all on display at one point. Now I think all they have is the Alaskan.
Their sloth bears were once referred to as "Ceylonese" sloth bears, though maybe that's "Sri Lankan", now?
They also published several articles & pictures, back in the day, featuring Asiatic black bears, though I could never locate the exhibit... I'm guessing they all passed away or were transferred elsewhere.
The Bear Canyon area of the zoo is, naturally, very tight on space, as it's literally built into a curved, downward-sloping canyon. It's one of the only areas to maintain the original 1916-style grotto exhibits. These were revolutionary for the time, with no bars or cages, but definitely leave something to be desired. The Safari Park has much more space for bears and other larger animals, I think. Their Asian lion/Persian leopard hillside enclosure (opposite the Sumatran tigers) is beautiful, lush, and spans several hillside acres. Ideal for bears. I also think on the tram tour, opposite the big savanna exhibits, there is plenty of opportunity for additional exhibits. Much of that tour consists of a one-sided viewing with empty fields on the other side. I know they're preserving native chaparral habitat... But they've made it this far, lol. They've developed 1800k acres already. Some ideas could be Eurasian bear species facing the Asian Plains or Eurasian Waterhole.