My advice is go with an open mind and you can have an amazing time wherever you end up. Everywhere has its beauty. If you engage the locals then you can't lose. Read up about the place but don't go with the guide book to much and you'll be cool and have some original adventures. If your travelling by yourself be safe but you should meet loads of people in the same position if youre not going to be in a very remote place. Common sense and friendliness goes a long way.
Heres a short summary of my experiences. When I took my gap year I went to Australia to visit my Godmother, Vanuatu to return to my birthplace (my parents were teachers with the overseas development agency and I stayed till I was 4 then moved to England), Fiji and then to New Zealand to meet another family friend and a final few days in New York. I went with my brother and New York was more so he could meet his girlfriend. I spent between a week and a month in most places and could have spent more time in the majority of places, particularly New Zealand.
In Australia Perth was a cool city and by all accounts the west coast is fantastic as is the south though didnt make it outside of Perth. Alice Springs was a bit depressing full of thoughtless tourists paying no attention to the down and out aboriginals and when we got to Ayers rock acting as though the signs saying please no photos were invisible. Our guide was a top bloke and had no time for disrespectful tourists. At the east coast we ran into the English backpacker culture and escaped it by going to a sleepy retirement town called Forster-Tuncurry for sea kayaking and bodyboarding. In Vanuatu we met old friends and caught up with many important people and saw a simpler way of life, ground oven cooking, cava drinking and outrigger paddling. Fiji was cool but again a backpacker place but the local diving guys were ace. New Zealand was a great country and hope to return one day. Great scenery, amazing things to do (kayaking, caving and so much more) you will not be disappointed. New York was a big bad city and I have to say I don't plan on going back. But even there I met some great people (most them South American and a Philippino) and saw an opposite way and impact of life to Vanuatu.
Since my gap year I've had the privilege to spend a week in the primary jungle on a university field course in Borneo at Dannum valley. Before this I spent time in the Philippines. The Philippines is a great country with many problems but the people were positive and unbelievably friendly. Never received so much generosity and genuine friendliness from people I didn't already know. Got taken out for meals, given free guides and helped with a villages fishing. The Philippines had mountains, caves, surfing, diving and hardly any backpackers (a friend and I saw one or two in the cities only) but sex tourists about. Borneo had amazing jungle, beautiful beaches, fabulous diving (Sipidan Island is in the top 3 in the world) and a lot of palm oil plantation.
SO many places to go though; South America, Sweden, Africa, Asia, Canada, Indonesia are just a few I want to head too, but I'm thinking I should calm down the old CO2 emissions now and am focusing on places closer to home. Hope the ramble has given you some ideas. Spent some long shifts in the fish and chip shop for runds but was all worth it and makes you appreciate it.