You didn't specify what age you are asking about so it was be different if it were as a child or as an adult on my own.
As a child the very First would be a trip to the Thousand Island area of New York State with my parents.
As an adult the First would have to be when I took R&R to Osaka, Japan while stationed in Vietnam.
Last major Vacation was in 2015 for a month long trek of areas of France, Italy and Spain plus a transAtlantic cruise from Rome to Florida.
Next in dream status at this point but a few are in the active research process but the primary goal is a Panama Canal Cruise.