Machu Picchu was awesome plus the floating islands on Lake Titicaca. Loved touring New Zealand for incredible scenery and wildlife. The Maldives for brilliant snorkelling. Could go on but restricted to 3.
I'm hoping to go in 2018 - I've already got a couple of trips planned next year (not with Riviera). Been to Vietnam and Cambodia with them and loved it. It wasn't a solo holiday but I found everyone so friendly that it wasn't a problem to be travelling on my own. Happy travelling!