Geodon is one of the atypical antipsychotics usually used for mood disorders, however it's not a mood stabilizer and doesn't work as well as one. I don't know anything about it other than what it is. Hopefully it will help your son. Just for your info: The first line mood stabilizers are: Lithium, Depakote, Lamictal, Tegretal and Trileptal.
Newer antipsychotics: Risperdal, Zyprexa, Seroquel, Geodon, Abilify
I have bipolar II: depression mixed with hypomania. I crave excitement too and get bored when life is too normal...lol. Fortunately, with medications I've learned not to give into that excitement buzz. Hypomanic is a real trigger for the "I need excitement" bug! If your son keeps drinking and using pot, the medications won't be able to help him. I'd try, the best you can, to get him to stop. If you feel he has a drinking problem, encourage him to go to AA or maybe even rehab. You probably already have though. The sad thing about grown kids is that we can only do so much.