FI and I have been discussing this and he told me to "take it the boards."
We consider ourselves to be Deists, and as such have chosen to have a secular ceremony.
We are debating if we should ask his Catholic Great Aunt if she'd like to offer a blessing before dinner. She does this before every meal, and will likely ask her table to join her in prayer as it is.
Both sides of FI family are religious by nature, Presbyterian on one side and Catholic on the other. Both sides have been a bit put off that we chose a secular ceremony, and I thought this could be a nice way to incorporate and respect the religious people in our families, without taking a vow based on something we may not believe.
My family isn't necessarily religious, but I do have a lot of friends who are. In addition to Christians, we also have friends invited who are Muslim, Jewish, Orthodox, Jadeist and Atheist. Great Aunts blessing would likely be Catholic-based.
Thoughts? FI is concerned a blessing based on Catholicism could alienate everyone who isn't Catholic and obviously we wouldn't ask her to do this and then dictate the terms of the prayer. When I was a devout Methodist, I was never offended by prayers based on a different religion, I just enjoyed the opportunity to pray. Now that I'm no longer religious, I usually just observe a moment of silence when in a group setting that is asked to pray.