I go to both China and Thailand and dont speak either language without a doubt Thailand is easier for everything.
I think if I'd been to China on my own It would have been very hard work even in Shanghai which is where I went.
Saying that, the last time I went just a few weeks ago, my Chinese contact arranged a visit to a sauna for us and I had a fantastic time, BBBJ,FS (twice) the lot, however If I'd been on my own I wouldn't have even known what the building was and nobody spoke any English at all.
My best advice is to go to Thailand, you really can't help but to get laid at any time.