Best - Europe - Ireland, stunningly beautiful beaches that would rival anywhere in the world. Venice, just stunning despite the crowds. Greek Islands, loved the relaxed pace and beautiful fishing villages.
Long haul - Stone Town, Zanzibar very atmospheric. Yosemite NP, clean fresh air. Maldives, perfect beaches. Kanchaniburi, Thailand, relaxing riverside town. Ubud, Bali perfect for people watching. Hong Kong, stunning skyline. Nepal, beautiful country with lovely people. Fiji, beautiful beaches and friendly people. South Island of New Zealand in winter, just stunning! The outback in Australia, atmosphere and eerie landscape. Australian beaches (too many to single out), beautiful to look at and amazing wildlife.
Worse places - pretty much most border towns around the world, full of crime and prostitution. Tacky Spanish Costa resorts, crowded beaches and British bars serving egg and chips. New Delhi, sterile, boring, people trying to mug you off and snobbery on a different level. Australian cities, not as interesting as the rest of the country, couldn't wait to get out into the countryside (probably more enjoyable if you live or work in them).