We visited Wat Pho (aka Reclining Buddha) after our visit to the Grand Palace. They are a few minutes apart, and you can walk it, but it’s easier just to take a short tuk tuk ride.
Wat Pho is one of the largest and oldest Wats in Bangkok and is home to one of the largest Buddhas. The Reclining Buddha (Phra Buddhasaiyas) is about 150′ long x 50′ high and quite impressive in person.
The Buddha the only real attraction at this Wat, so it’s a pretty quick trip, except for jockeying with the crowd to get a good view and a photo.