Beijing is not the place to make your first experiment in traveling with small children, although it's a better choice than anywhere else in China. Your biggest challenges will be the lack of services or entertainment aimed at children, the lack of familiar foods outside the bigger hotels and fast-food chains (unless your children have been brought up with Chinese/Asian food), and hygiene.
Some children find Chinese strangers a little too hands-on, and may tire of forced encounters (and photo sessions) with Chinese children met on the street. But the Chinese put their children firmly first, and stand up on buses while the young ones sit.
China is grubby at best, and for children who still have a tendency to put their hands in their mouths, constant vigilance will be necessary, or constant toilet visits will result. Older children should be instructed on frequent hand washing and special caution with food.
Some familiar Western brands of disposable diapers, along with familiar creams and lotions, are available in Beijing.
Beijing hotels generally don't charge for children 12 and under who share a room with their parents. Almost all hotels will add a bed, turning a double room into a triple, for an extra ¥80 to ¥100, which you can often bargain down.
Although babysitting services are not uncommon in the best hotels (the Sino-foreign joint ventures with familiar names, in particular), in most cases the babysitters will speak very little English or none at all, will have no qualifications in child-care, and will simply be members of the housekeeping staff.
All restaurants welcome children, but outside the Western fast-food outlets, some Chinese copies of those, and major hotels, don't expect highchairs or special equipment except very occasionally. The general Chinese eating method of ordering several dishes to share will at least allow your child to order whatever he or she deems acceptable (although it will not taste the same in any two restaurants), while allowing you to try new dishes at each meal.
Although Chinese food in Beijing is different from (and mostly vastly superior to) Chinese food served in the West, it would still be wise to acclimate children as much as possible before leaving by making trips to the local Chinese restaurant. In many cases only chopsticks will be available, so consider taking forks and spoons with you to China. You can now find McDonald's (complete with play areas), KFC, and Pizza Hut in Beijing, and almost all hotels of four stars or up have coffee shops which deliver poor attempts at Western standards.
Keep in mind that although Western cooking is available at many excellent Beijing restaurants, authenticity comes at a price. Cheap bakeries, however, often sell buttery cakes and close relatives of the muffin containing raisins and chopped walnuts.
In general, attractions for children are few, and exploring temples may quickly pall. Success here will depend upon your ability to provide amusement from nothing, and the sensitivity of your antennae to what captures your child's imagination.
Discounts for children on travel tickets and entrance fees are based on height, not age. There are variations, but typically children below 1.1m (3 ft., 7 in.) enter free and travel free if they do not occupy a seat on trains and buses. Children between 1.1m and 1.4m (4 ft., 7 in.) pay half-price. Many ticket offices have marks on the wall at the relevant heights so that staff can quickly determine the appropriate price.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.