harp -
Welcome to Flyertalk. The idea you propose is inviting, but AmEx does not count mile transfers toward mile accumunlation. I agree with everyone else...find what airlines fly the most direct routes to where your son will be at and where "home" is and go from there. All airlines have affiliated credit cards. Most also come with sign up bonuses of 5000-10000 miles and you can also link your phone lines to these accounts too (Northwest and Sprint, Delta and MCI, etc.) These phone sign ups also come with bonuses and you usually get 5 miles for every long distance dollar spent. In addition, use the card for other purchases as each dollar spent equals one mile.

Best of luck.