I follow two principles in splurging on travel:
First, being able to take more trips is my primary way of splurging. My wife and I enjoy multiple smaller, weekend or 3-day trips every year, plus at least 2 (and sometimes 3) longer trips. Many trips we plan at the last moment; we enjoy the flexibility and spontaneity. Making reasonable choices on each trip allows us to travel more.
Second, I always ask "If I pay more do I get more? (And is it something I value?)" There are countless ways to spend money without getting much in return for it. Feeling I'm wasting money is one of the biggest obstacles to my enjoyment. But that doesn't mean I'm cheap; it just means the cost has to be in line with the benefit to me. For example, I'm content to stay at an inexpensive but comfortable two-star hotel when I'm planning to all day touring or sightseeing somewhere else. But if it's a beach trip, I'll pay to stay in a nice resort on the beach because being steps from the sand is worth it to me.