Most international flights arrive at Orlando International Airport. Orlando also has a second airport that also serves international destinations, Orlando Sanford Airport, which is situated about 25 miles outside Orlando.
Many Orlando hotels and the Walt Disney Resort offer a free shuttle service from Orlando International Airport, although reservations are often required. Local buses serve most of the tourist areas for about $2 one way, or you can take a shuttle bus. As shuttle buses cost between $18 and $45 per person for a return journey it might be worth hiring a taxi, especially if the whole family is in tow. You can also pick up car hire at Orlando Airport, and considering that all the major resorts have ample parking this is often the easiest way to get around.
Most people decide to hire a car when they visit Orlando, but if you want to avoid driving there are still ways you can get around. Firstly, check whether your hotel offers free shuttle buses to any of the attractions, many of them do. The local bus network is also fairly comprehensive, if a little slow, but it's really cheap so if you've got the time this is a great option. Also, for travel along International and Universal Boulevard, the i-ride trolley offers regular cheap services.
If you're looking to travel a little further, trains depart to both New York and Miami, serving some interim destinations. The greyhound intercity buses also offer low cost travel to a wide range of destinations. Public transport is fairly limited to major towns and cities though so if you're looking to head off the beaten track or want some more freedom then hiring a car in Orlando is again your best option.