Debbie,
We brought our son with us when we adopted our daughter in Taiwan. He was three at the time and I so glad we brought him. He still talks about going to the "baby house" and he enjoys telling his baby sister about Taiwan. He really felt involved in the process of the adoption and I think it has also helped with their sibling relationship. Another thing to consider is how much travel experience your family has had. We have been traveling a lot with our son since he was a baby (we spent his first three years in Japan) so the long airplane trips, local transportation, and hotel stays weren't overwhelming for him. And one final thing to consider is the country. We considered travel when we were trying to decide which country to adopt from. We knew early on that we wanted to bring our son with us so we researched the saftey issues, health issues, and required travel times of each country we were interested in. Every family and every child is so different. It is a very personal decision and I am sure you will do what works best for your family when you get to that point. Good luck on your adoption journey!