I have done both methods. I think cuttings are easier. I can get a cutting to grow to a 5' plant in no time the next year. Probably "a plant light" wasn't enough light. I had blooms in January/February in the basement when I brought in a whole plant.

I prepared some pics on this subject for a friend awhile ago.

Overwintering Brug pics

I cut mine down and keep almost dormant - little or low light, cool, watering only occasionally. I haven't taken mine in yet, as they are still blooming like crazy.

You should also check out the Brugmansia forum - they have a lot of really knowledgeable people and there is often a post on how to over winter around this time of year.