To me, the early 1970s were the best time for Thailand, especially the period between the overthrow of Thanom Kittikachorn and the Counter-revolution in 1976 (things became pretty bad after that). The country was prosperous, there was still land available in the Northeast, people were optimistic, and freedom was rampant. A saying of the time was, "Thailand has kept more freedom by accident than America has by intention." And, really, life under Kittikachorn wasn't bad, either. Especially after he conducted a coup against his own government.

An alternative was the period while Prem was Prime Minister. There was less fun, but he cut back corruption greatly

When Bangkok became the home of the Thai monarchy in 1782 and established the Grand Palace as the official residence and seat of power.