Boston Harbor Hotel, Boston
Boston Harbor Hotel stands sentry over the city's historic waterfront area, taking pride of place in Rowes Wharf (if you want to be really flash, you can get a water taxi from Logan airport and pull up outside). Its 230 rooms are luxurious but, for a five-star hotel, fairly dated, with brightly-patterned bedspreads and flouncy curtains. It makes up for the décor with snappy service and a stunning location; the harbour-side rooms have some of the best views of the water you can get without climbing rigging.
Boston Harbor Hotel, 70 Rowes Wharf, Boston, US (00 1 617 439 7000; www.bhh.com). Doubles start at $288 (£160), room only.
Four Seasons, Hong Kong
Set just back from the waterfront, with spectacular views of Victoria Harbour (especially from the rooftop infinity pool) and the city's sky-scraping financial district, the Four Seasons is one of the most glamorous hotels in a city not exactly known for shabby chic. Its 399 guest rooms are decorated in signature Four Seasons style, with wood and silk-panelled walls, hi-tech amenities and wall-to-wall windows. In the unlikely event that you want to escape, it's minutes away from both Hong Kong Station and the famous Star Ferry.
Four Seasons, 8 Finance Street, Central, Hong Kong, China (00 852 3196 8888; www.fourseasons.com/hongkong). Peak View doubles start at HK$4,294 (£280), Harbour View doubles from HK$4,859 (£316), both room only.
Hotel Tresanton, Cornwall
There's nothing grandiose about the harbour in St Mawes. Small, pretty and resolutely British, it caters just as well for the bucket-and-spade brigade as it does for small boats. Not that the surrounding accommodation is as low-key. Olga Polizzi's glamorous Hotel Tresanton features antique furniture, local art and views over sparkling blue sea. The 29 rooms all have views of the water and have been furnished in the kind of breezy, relaxed style that signifies painstaking design. For the best views, book in for dinner on the restaurant's outdoor terraces.
Hotel Tresanton, St Mawes, Cornwall (01326 270 055; www.tresanton.com). Doubles start at £170, including breakfast.
Westin Bayshore Resort, Vancouver
Vancouver's harbour is one of the world's most spectacular, surrounded by mountains on one side and ocean on the other. If you want to stay somewhere that offers a panoramic view from your bed, the Westin Bayshore is hard to beat. Rooms in the upgraded Tower building have private balconies, while those in the main building have floor-to-ceiling windows. Describing itself as a downtown resort, the Westin Bayshore provides easy access to the city as well as more relaxing activities such as bike rides in neighbouring Stanley Park and swimming in the indoor and outdoor pools.
Westin Bayshore Resort, 1601 Bayshore Drive, Vancouver, Canada (001 604 682 3377; www.westinbayshore.com). Doubles start at C$185 (£81), room only.
The InterContinenal is a chic hotel set in the city's heritage-listed former Treasury Building. Originally built in 1851, but now featuring a sleek modern extension, it's right opposite the Royal Botanic Gardens with dramatic views of Sydney Harbour. Many of the hotel's 509 guest rooms have window seats looking out over the water, but real show-offs should book the Australia Suite, which has an open-air terrace. Other spots with wrap-around harbour views include a striking rooftop lounge (access for executive guests only) and a 31st-floor pool.
InterContinental, Corner of Bridge and Phillip Streets, Sydney, Australia (0870 400 9650; www.sydney.intercontinental.com). Doubles start at A$292 (£117), room only.