There are some good ideas in this thread, it is also worth checking out the gw pvx wiki, and looking in their hero builds section - as the common builds are listed there. They can all be tweaked, but they give you a rough idea of what each hero profession is good at, and what the AI can accomplish. Once you have that down, you can fiddle with their builds to your hearts desire, letting you be adaptive.
They can be very stupid however, so as Alaris said, learning to use flags helps. Even just an initial placement and then cancelling and letting them move again can help a lot.