One interesting difference that Garfield's survival might have made (from an old soc.history.what-if post of mine):
"In November 1883, Haiti's president Louis Lysius Félicité Salomon, bedeviled by irate British creditors, tried to solve his country's financial problems by offering Mole St. Nicholas to the United States. This was an excellent anchorage commanding the Windward Passage between Haiti and Cuba, but the Arthur adminstration was not interested in acquiring it. (Not that Arthur and his Secretary of State Frelinghhuysen were by any means always cautious in foreign policy. Toward the end of the Arthur administration, they became very bold indeed--they wanted a Nicaraguan canal and for that purpose arrived at the Frelinghuysen-Zavala treaty which would have established a virtual US protectorate over Nicaragua. Even Blaine thought that this was going too far. But Arthur and Frelinghuysen were not interested in acquisitions in the Caribbean islands.) On February 1, 1884, Frelinghuysen informed his envoy at Port-au-Prince that the US had never deemed it necessary "to maintain
impregnable fortresses along the world's highways of commerce." In words that would infuriate Mahan he added "Even as simple coaling stations, such territorial acquisitions would involve responsibility beyond their utility." If Garfield had not been killed, and Blaine had still been Secretary of State, the US reaction might have been different--though there is still the question of whether a treaty would have been approved by the Senate...
"The problem was that when the Haitian government was most anxious to offer the Mole to the US (1883) the US was not interested; and that when the US did become very interested (under Harrison) the Haitian government was just too
afraid of adverse public reaction to agree to the terms the US wanted.
"Question: If the US had obtained the Mole, would it have found it necessary to get Guantanamo Bay after the Spanish-American War? After all, it would seem that the Windward Passage could be as easily commanded from the East as from the West. OTOH, the US might well still have felt that what it regarded as its extraordinary interests in Cuba required a base actually on Cuban soil..."
https://soc.history.what-if.narkive...e-in-1880s-or-1890s-part-one-mole-st-nicholas