Traveling across the Pacific Ocean would be the longest distance to travel, since it is the largest ocean by square milage, although it would be possible to combine different routes to increase the distance traveled elsewhere.
In Puerto Rico it was useful, in Cuba not so much. Cubans perceived the outcome as occupation and didn't want to have United States occupation in their country. Puerto-Ricans had a form of a civilian government with independence and Puerto-rican citizenship but the country belonged to US.
A directly stated consitutional requirement in the US constitution in Article 2 Section 3 is that the President must give to Congress recommendations regarding the State of the Union and recommend any actions that are considered essential and expedient.
a. because it is relatively stable
