Grand Tjokro Hotel is probably the best hotel in town. The rooms are comfortable but very small. Unfortunately, the pillow and sheets in my room smelled like sweat, ewww. Also, the staff in the restaurant took so long to make a hot coffee. . . but there isn't really a decent coffeeshop in Klaten.
The hotel is situated on a busy road connecting Yogyakarta and Klaten. You can walk along Pemuda road to find food and get a sense of "small town" Javanese life. Check out the delicious and cheap Ayam Penyet Suroboyo about 5 minutes from the hotel!