If you are going off the beaten track or want to do something fairly unusual or exclusive - white water rafting on the Orange River ? - then it is worth trying one of the specialist agencies eg
http://www.steppestravel.co.uk '.a leading “off the beaten track”, tailor-made tour operator, operating around the world since 1989.'
www.coxandkings.co.uk 'from the luxurious to the adventurous'
www.abercrombiekent.co.uk 'pioneers in luxury travel'
www.pageandmoy.com 'quality escorted holdiays'
www.vjv.com (Jules Verne) 'classic journeys throughout the world'
www.noble-caledonia.co.uk 'trips that are educational, enjoyable and above all, different.'
www.martinrandall.com 'art - architecture - gastronomy - archaelogy - history - music'
http://www.orpheusandbacchus.com/ classical music and wine