City regulations limit the number of bodies—however small—that can be crammed into a room. The rule varies from hotel to hotel, but if you're told a room is for three, believe it. Ask for connecting doubles or look for "family rooms"—which typically sleep four or five. To get help, try the London Tourist Board's booking service (44-171/932-2000; http://www.londontown.com), or one of the many on-line services (two to get you started: http://www.hotelnet.co.uk and http://www.ase.net).
At the top end, the newly remodeled Mandarin Oriental Hyde Park (66 Knightsbridge; 44-171/235-2000, fax 44-171/235-4552; doubles from $405) supplies in-room coloring books, toys, and videos; special menus; and a teddy bear to keep. 22 Jermyn Street (22 Jermyn St.; 44-171/734-2353, fax 44-171/734-0750; doubles from $340) is an antiques-filled, family-owned 18-room hotel. Owner Henry Togna even puts out a children's newsletter, and there are books, videos, and puzzles (and Sega games on request) to keep them occupied when they're not relaxing in their teddy-bear dressing gowns. Beautifully constructed in a former government building across the river from Big Ben, the London Marriott (County Hall; 44-171/928-5200, fax 44-171/928-5300; doubles from $305) opened last fall. Kids dig the multichannel TV's, the 25-meter-long pool, and the fact that the London Aquarium is downstairs; parents like the frequent package deals. At the spiffy Athenaeum Hotel & Apartments (116 Piccadilly; 800/335-3300 or 44-171/499-3464, fax 44-171/493-1860; doubles from $440) the Mary Poppins package puts children ages 5 to 10 in the care of a real British nanny for an extra $150 per day, with trips to all sorts of attractions. Finally, what teen wouldn't want to stay where the rock stars rock and the models promenade?Overlooking Hyde Park, Metropolitan (19 Old Park Lane; 44-171/447-1000, fax 44-171/447-1100; doubles from $340) is state-of-the-art minimalist. Besides, what could your two-year-old break that a rock star hasn't already trashed?Then there are the more reasonable options. Recently refurbished, the Basil Street Hotel (8 Basil St.; 44-171/581-3311, fax 44-171/581-3693) has family accommodations—two bedrooms sharing a bath—from $405, with discounts for stays of more than five nights. The Cranley Gardens Hotel (8 Cranley Gardens; 44-171/373-3232, fax 44-171/373-7944; doubles from $180, including tax and breakfast) is well-placed for the V&A and the Science and Natural History museums. Others to keep in mind: Five Sumner Place (5 Sumner Place; 44-171/584-7586, fax 44-171/823-9962; doubles from $199, including breakfast); Windermere Hotel (142144 Warwick Way; 44-171/834-5163, fax 44-171/630-8831; doubles from $165, including tax and breakfast); and Abbey Court (20 Pembridge Gardens; 44-171/221-7518, fax 44-171/792-0858; doubles from $215, including tax and breakfast).
Children have their own hotel at Pippa Pop-Ins (430 Fulham Rd.; 44-171/385-2458, fax 44-171/385-5706; from $123 per child), where those from 2 to 12 can overnight in a town house (the baths have rubber duckies). It might be better than leaving your kids with a sitter you don't know, should you decide to go out without them.
Renting a flat—or even a town house—can be more cost-effective. The Apartment Service (44-181/944-1444, fax 44-181/944-6744; http://www.apartment.co.uk) has studios and one-bedroom flats in 2 Hyde Park Square (from $130 a night). Go Native (44-171/221-2028, fax 44-171/221-2088; http://www.gonative.co.uk) will place you in a flat belonging to an absent Londoner, with some properties specially earmarked for families (each is stocked with a guide to area restaurants, shops, and sights, as well as a tip sheet for families—one of the owners, Guy Nixon, has kids). A flat in Little Venice, for example, opening onto acres of communal gardens with swings and a tennis court, goes for $1,320 to $1,820 weekly, fully inclusive.