Had an inquiry regarding a 30 day stay accommodations. The videos below are recent youtube uploads, which might be an alternative.
It's all a matter of what you want to spend and where you want to be. Most hotels offer long stay discounts. Then of course the are apartments starting at around 2,000 baht / month, plus utilities. Most likely you'll be eating out regularly in that case.
Bangchak Phuphan Resort
Baan Phra Chan