If you want so slightly cooler (4-5C) temperatures you should stay in the Khao Kho district in preference to Lom SaK. Drive up HWY 12 to Camp Son (post office spelling, Khaem Son on Google maps). More than a thousand resorts to choose from, from shoe boxes to 5 star. You will also be near the biggest temple in the area, Wat Phra Thart Pha Sorn Kaew, but try to visit on week days as the weekends can be crowded.