No, no I was not at all implying I would like to do this in the Betazoid custom. I would imagine a certain degree of formality, though without the religious element it might be a bit more subdued (i.e. even the daughter of a textile tycoon probably isn't spending half a year's income on a dress she'll wear exactly once, a custom I still cannot begin to fathom in our world). For my own sake I could see appearing in the equivalent of a dress uniform (since we are still technically part of the Guard) or civilian formal wear, but again that's pretty close to home. Obviously it should be an occasion that calls for unusual dress, I'm just not certain how unusual you'd like to go; it is your world after all.
I'll explain that, while I did work for Chief Thomas a bit longer as a junior investigator - several months as opposed to a handful of weeks - I never worked with him directly quite so closely. I worked with a handful of senior investigators and spent most of my time either eyeballs deep in paperwork or out on street, whereas I have seen and worked with Captain Peter himself just about every day through some of the most mind-bending bookkeeping and planning I've ever done in my life (assuming the notes I've put to text here represent the Reader's Digest version of what we've actually done and not the whole of it), so I feel he would be the more appropriate person to ask, especially when you consider I haven't seen Chief Thomas since our little operation got under way and he may well have forgotten me by now.