Often described as the Venice of the East thanks to its elaborate network of canals, a boat ride is just one of many activities the top guide books tells travellers they must experience while in Bangkok.  Other 'must-do' activities include a visit to the Grand Palace and the Thai capital's many temples (of which there are literally thousands). What you might not expect to make the list however, is a Chocolate Buffet.  But the talents of Swiss-born executive pastry chef, Laurent Ganguillet have become legendary. In the Sukhothai's Lobby Salon on Friday, Saturday and Sunday afternoons the highlight of afternoon tea is Ganguillet's trolley of 15 raw chocolates presented in order of cocoa and milk concentration. They include Valrhona's bitter Mariage de Grands Crus' Abinao, a robust African blend containing 85 per cent cocoa, Valrhona's Aranguani, a Venezuelan couverture (72 per cent cocoa blend) with a hint of liquorice, raisin and chestnuts and the Jivara, known as the 'Grand Cru' of milk chocolate. Each can be melted over a low flame and served as a hot chocolate drink with a generous dollop of cream on top.