I believe that if you visiting Guangzhou in a wheelchair, go to ZHU JIANG XIN CHENG (Pearl River New Town) is the best choice, since the accessibility facilities are better.
For instance, you can overlook the whole Guangzhou on Guangzhou Tower, get some information about Guangdong history in Guangdong museum. Also, you can attend classical music concerts and operas in Guangzhou Opera House.
Since many traditional tourist sights have steps or something like that, I don’t recommend you to go there.
But I really recommend you to try different foods in Guangzhou. Many restaurants are wheelchair accessible. And foods in Guangzhou is famous.
I asked one of my friends, who lives in Guangzhou with his wheelchair. He says that many of the older tourist sites have improved the accessibility. For instance, Chen Clan Academy used to have some doorsill, but now visitors can pass the door with their wheelchairs. Other places also have elevators for wheelchair users.
When I talked with him, I realized that Guangzhou has progressed a lot. I will try to go there at my leisure and give you more information.