But this isn't Jackie-O jetting off with a few friends and couple of secret service guys in 1962. Even if a significant portion of these trips is paid for out of pocket (but even that's up for debate as FOIA requests are either just now being responded to, or pending), we live in a post 9-11 world and the security detail and all that goes with it is very expensive. The Spain trip cost nearly $500K of taxpayer money for security detail, the Air Force Jet and housing the crew and the like. In a post 9-11 world it's much harder to get that information, and suffice it to say it's 1A: Security Concerns. 1B: Political image concerns.
The information on many other trips has proven very difficult to ascertain, but if estimates on the cost of pre 9-11 trips to the same places are carried forward to relative costs in 2014. It's costing a ton.