I’m a big fan of off-season travel. In fact, you can read my quotes on this topic in today’s ABC News. There are some obvious reasons to hit the road off season: Flights and hotels are much cheaper. For example, I'm planning a trip to the Out Islands of the Bahamas in 2011 and I'll looking to go in May when hotel prices drop significantly.I also visit Vail and other ski areas in the summer when I can stay in at the resorts for a fraction of the cost and go hiking and mountain biking on the slopes.
As far as the crowd issue goes, I travel to Portugal a lot and I love going during the low season when the weather is still mild. And, unlike in the high season, it's easy to get reservations at some of the best restaurants in Lisbon during this time. Another plus of traveling during low season is that you can get more of a feel of authenticity and engage in more mingling with the locals. For example, I visit Reykjavik in December and January when there are only a few hours of daylight. And yet this is a perfect time to hang out in the cozy coffee shops and bars with the locals and chat about politics, the economy, design and art -- topics they love to talk about.
The low season is also a great time to experience local festivals that only occur at that time of the year. For example, in Croatia, the truffle festival in Motovun takes place in November.