Sounds like a good plan! I would definitely recommend staying inside the park, Epcot being one of the most spacious parks at WDW with ample walkways and many "hidden gems" has TONS of great areas to sit and relax. Here are some of my recommendations and "quiet spot" ideas:
- Bakery in France (Both indoor and outdoor seating, note that sometimes this area can get crowded after the Impressions de France film gets out)
- France Gardens (Outdoor garden area located to the right of the perfume shop with views of the International Gateway canal)
- Waterfalls at Canada (There are beautiful outdoor areas with benches just outside of the entrance to O Canada attraction)
- Japanese Gardens (Outdoor Zen Gardens and Ponds between Katsura Grill and the large Pagoda)
- English Gardens (Plaza in front of the Paul McKenna Band stage, note that this area is quiet only when there are no shows playing on the stage)
- Indoor Breezeway on the East side of Future World (Indoor air conditioned area behind Starbucks and Club Cool)
- Outdoor garden area in front of Ellens Energy Adventure (quiet benches in front of former Wonders of Life Pavilion)
Hope this helps!