I spent 3 weeks in Jinghong and Xishuangbanna, during the Spring Holidays.
The "Lonely Planet" still recommand the "Forest Cafe" and its so-called "hamburger". Well, don't even bother to go there. The staff is not friendly at all, the food horrible. Prefer the Hometown Cafe (which is next to the Forest). For foreign and Dai food, go to the MeiMei or the Mekong Cafe in Manting Lu. Explore the others streets, where there're plenty of cheap chinese restaurants.