Nick, as
@Rob***
, pointed out; given your travel history to/from thailand, a year-long, multi-entry Non-O visa would be the best "fit" for you.
If you can't get one from the thai consulates in China, you can get one easily from the Thai consulates in Savannakhet Lao, Ho Chi Minh City Vietnam and Seoul South Korea with minimal documentation and no need to show proof of funds.