I starting collecting airline miles several years ago with a USAA credit card, which accumulated miles based on yearly spend. My first big trip was with my sons to Europe for a month, using my National Board stipend money and some miles. But then I started getting offers for bonus miles when opening different cards. Those various cards through the years have paid for trips to twenty-six countries! Some of those trips were to multiple countries, like the summer of 2008 to Greece, Italy, Croatia, Slovenia, and Switzerland. That trip took lots of planning!
Some miles paid for the entire trip and some just one way; I remember paying $30 for a one way ticket to Italy using the last of my Continental miles!