Some fair points, but remember that the US had the benefit of knowing that post-WW1 settlement was a failure. Of course, Wilson did object to the conditions of the Treaty of Versailles, so it's fair to say the US had a better perspective from the start -- though one can argue that the US' own failure to ratify the League of Nations was a contributing factor to WW2.

Another key factor is that the US had no empire to hold together, and, to its credit, wisely did not seek to expand its territory after WW2 in order to create one (which it could have easily done, and which the UK had done many times before).