You could argue that whether or not a vacation makes you happy has more to do with you than with vacation. On the whole, studies have shown a link between extroversion and happiness. So, when it comes to extracting joy from vacations and pre-vacation anticipation, it seems extroverts would have a leg up on introverts.
But other personality traits also may predict how much a person winds up enjoying a holiday. For example, one study showed that "optimism" and "hopefulness" correlated strongly with a person's perceived ability to derive pleasure through anticipating a future vacation. Not surprisingly, a person who looks forward to his or her trip with a "can't wait" mentality derives more happiness from anticipation of the vacation than a neurotic person who fears the vacation won't go well. A hopeful, optimistic attitude was also a good predictor that the person would enjoy the vacation while he or she was actually on it [source: Bryant]. So, if you think getting too excited about your trip beforehand guarantees you'll be let down while you're on it, think again.
On the other hand, the study showed that participants who had higher "reminiscing" scores -- meaning they perceived themselves to be very good at deriving joy from recalling happy memories -- were more frustrated and disappointed with their vacations while they were on them. Perhaps thinking about old times while on vacation makes present times seem less than perfect [source: Bryant].
Since eager anticipation of a trip is so much a part of what makes people happy about vacations, it pays (in happiness levels) to be able to think positively, rather than neurotically, about something that hasn't yet happened. In fact, one study showed that participants' overall well-being improved when they simply took time to imagine future events in a positive rather than negative light once each day [source: Berkeley].
What better thing to imagine in a positive light than your trip to Aruba? And speaking of Aruba, what else can you do, besides practicing positive thinking, to make sure it's a happy trip?