Sukhothai has a little holiday feeling about it. Esp. As it is on the main road and away from shops, street hawkers. It has beautiful gardens, water features, and the room opens onto the garden.
If you are a gym person, the 4-season gym is better and the 24-hour gym is on top.
Sukhothai's public areas are larger, more places to sit, read, and relax.
The four seasons are very good, but there is less area to spend time in addition to the lobby area.
It all depends on your accommodation plan. For a more romantic vacation, I will go to Sukhothai.
The Sukhothai tries to recapture that glorious past in the middle of modern Bangkok with a profusion of teak, silk, and Buddhist stupas in its magnificent gardens.
This "understated and underrated hotel," set amid six acres of gardens in the diplomatic nexus of Bangkok, is "an oasis of calm, removed from the hustle and bustle."