I normally cycle weekly, and range from extreme excitability with poor judgement through to suicidal depression. My pdoc chose to put me on lithium because it is effective for mania, and is also known to reduce suicidality. So far so good (checks pulse). She put me on Epilim to help with the reduction of mood swings. The combination only achieved moderate mood intensity. I was then put on Seroquel (again) for psychosis, and that is when my mood chart flat-lined on normal for a couple of months so far.
While the cycle frequency is typical of Bipolar II, the mania is what got my pdoc to diagnose Bipolar I.