On the site of Termales de Santa Rosa, Hotel Termales offers accommodations in a sprawling mansion with one old, renovated wing and two newer wings. Prices include access to both parts of the thermal complex: Termales de Hotel and Termales Balneario, and you can hit the pools at 6am, before day-trippers arrive.
The Finca rooms are comfortable but simple; the accommodations in the adjacent Montañas block are only slightly more expensive but are far superior, with more space and waterfall views. The most luxurious rooms are in the Cabaña block, which has a private thermal pool on an elevated deck overlooking the river.