I went to a religious, semi-private event that took place in Vietnamese, Mandarin and English. It was mentioned that dragons are significant because they fly, and are thus, closer to Heaven than the other animals that show up every year.
There was some Vietnamese music and dancing. The dancing was movements of slow waves that went in stops and starts. This was also a time when expensive silk outfits are worn.
At the end, people got to take an envelope from a money tree. It was a bare tree in a pot, with red envelopes clipped on. It symbolizes prosperity for the coming year. I had originally thought of taking one, but there were so many little kids that I didn't dare.