As far as I can tell, weddings using traditional Chinese cultural elements are popular in California, especially in the San Fransisco area. As can be seen, News Years is still also important here. This area of the US has a large affluent Chinese-American population and has wedding planners that specialize in serving this group. For example, from one photographer's page:
In America, from my experience at least, the amount of traditions followed at Chinese weddings can vary significantly depending on what the bride and groom choose to participate in or in some instances, what the parents of the bride and groom require. Most 2nd or 3rd generation Chinese weddings in america only have certain aspects mentioned above mixed in with a western style wedding. For inter-racial weddings, the Chinese bride or groom usually includes some of the tradition as a sign of respect for the chinese heritage and culture.
The elements mentioned are: a 12 course banquet of shark Fin Soup, Abalone, Roasted Pig, chicken, fish, and lobster, red wedding dresses, dowry, tea ceremony, etc.
It's not my understanding that this is common in most parts of the US. So, while white weddings become more common the longer the family has been in the US, it's probably more important if the family lives near a large American-Chinese community preserving the traditions. However, non "traditional" white weddings are more common all the time. They are common enough to not be seen as anything unusual, either. Wedding magazines specific to Chinese-Americans are published about these issues and might be a very good source to look into.
In the US, a couple may obtain their legal paperwork for their marriage, known as a marriage certificate, from either the court house or from the marriage officiant. I imagine in China, it is still require to obtain paperwork for a marriage to make it "legal." Religious clergy marry couples and then obtain this paperwork and the work doesn't have to be done twice. The Catholic Church originally claimed the right to declare the validity of marriages and divorces (or rather annulments) so this is why it is allowed. To disallow religious discrimination, any religious or non-religious person may purchase a certificate to marry couples in the US or you can be married in the court house. Based on my personal experience of 4 court house weddings-not all mine mind you- this takes about 30-45 minutes, so skipping the wedding officiant is not a big obstacle.
Update: I found a little more info on this
The wedding officiant is derived from Christian tradition, which is derived historically from Catholic Church tradition. In the Catholic Church there are 7 sacraments performed by priests. The sacraments performed today were chosen during reforms of 12th century. The sacrament of marriage is a bit different in this case than other sacraments since its blessing/solemnity is derived from the mutual love of the couple as a reflection of God's love and his Christian Church. The marriage vows have the purpose of making the marriage holy. It is not given through the priest.
Before instituting the sacrament, most people did not use a priest for wedding services, even though church weddings did exist, since the priest isn't needed. This caused problems later, since if it could not be proven that the bride and groom were of age (12) at this time, the marriage was consentual (bride kidnapping and forced arranged marriages did occur) or if the witnesses could not be produced, the marriage could be annulled. Parents were often furious their children would get married in secret without their consent. The famous play Romeo and Julliet is an example of the ease of these secret Middle Ages marriage. So, formalizing marriage help stop these problems.
The role of the priest historically as officiant is as the celebrant of the mass and of the marriage with the couple. During mass, the Eucharist is "celebrated." That is always important to Catholics since it is spiritual nourishment and so it is done on pretty much all occasions. In the Middle Ages in Europe, the parish priest would have had a central role in the community, so he would not at all be someone the family and couple didn't know. He would have been a well respected authority figure. Everyone would have known the priest and so everyone would have starting coming and witnessing marriages, leaving little doubt about who was really married.
As far as I know, all modern Christian churches maintain marriage as either a sacrament or a similar ceremony celebrated by a pastor. The usage of a religious authority to bless marriages seems quite common for most religions, as well. Jews, Hindus, Muslims, Buddhists, likely most Native American religions use an officiant, so they are quite common amongst ethnic minorities in general. In those cases, the ethnic minority group will just have their traditional wedding ceremony.
Sources: BBC. "Medieval Lives: Damsel" Very entertaining. Discusses bride and groom kidnapping.
BBC. Medieval Lives Birth, Marriage and Death. A Good Marriage