Xiamen Wyndham Hotel    Wyndham Hotel Group, the largest US-based hotel company in China and the world's largest hotel company with more than 7,100 hotels under 11 brands, today announced that it has signed agreements for an additional four hotels in China.   Currently under development, the properties include the Ramada® Sanya hotel owned by Hainan Mingboda Real Estate Co. Ltd.; Ramada Plaza Wenzhou hotel owned by Wenzhou Tianrun Real Estate Development Co. Ltd.; Ramada Longyan hotel owned by Fujian LongYan Yifeng Hotel Co. Ltd.; and the Ramada