Sukhothai hotels, boutique hotels, resorts exist in the new part of the city and nearby the old city. Keep in mind that the old city is about 12 kilometres from the new city. But there are plenty of inexpensive local transport options like tuk-tuks, Songtaews (shared taxis) or motorcycle taxis that can get you around the town easily.
Hotels in Sukhothai new city are good value and even offer free pick-up from the bus station and free use of bicycles. There is something for every budget. Higher-end resorts and boutique hotels are located closer to the old city.