C.J.
Our church does this too and I have seen the parents dress the children in a range of outfits, but the one thing I haven't seen (as in other churches) is the full christening gown. Usually cute matching outfits that are in-line with the dress of the service/church. during summer cute short sets or bubbles for boys and dresses for girls.
I love Snug as a Bug for nice, not too trendy, matching outfits and ideas.
Best and congrats on the dedication of your babies. A very moving experience to have an entire congregation stand up and pledge their support to you and your family's walk with Christ.