Wha-? I thought I sensed my name being invoked.....
Ahh, I see it was the irrepressible Mimi, again seeking wisdom on the behalf of others...
Well most of it has been said, but first, with Oysters and Crawfish I'm not as concerned as I might be had it been say, crab and lobster. The shrimp however, I do envision greatly outweighing those two in popularity, I would therefore anticipate a heavy demand on that. And shrimp isn't cheap anymore, and I agree with Mimi and Billy that any seafood buffet must be regulated. (and for some reason chopped fruit as well--they always just INVADE the dang fruit bowl.)
The sides and condiments can be put out self serve, and of course FIRST. Basic rule in event catering is to get as much on the plate first, before the guest hits the protein station. This helps prevent the last 2 dozen people in line screaming like banshees cuz "the meat's all gone!" while 48 fingers all point at YOU, instead of their table mates with piles of seafood heaped on their plates.
There are a couple ways to do a seafood sandwich buffet so it still "feels" like a sandwich bar....
The first is as Billy suggested, MAKE an assortment of small sandwiches for the self serve buffet, and again,
put them as the last selection. (If its a line, this will work, if they're "stragglers" they may well go for the sandwiches
first.) If this still doesn't feel right,
The second way (and best IMO) is to offer their bread and garnishes on the self serve buffet table, they transition to the attended buffet action station, where you or your pleasant servers will gladly heap up (per your portion control) their open bread with the meat of their choice.
As a side note, you WILL get people who aren't happy with how much you put on their sandwich--in those case, you just.....add a little more. The'yre happy, and sure, the guy behind them may notice and ask as well, but that "trend" will end shortly--you're not out much and you have satisfied another basic rule.....try to give the guests what they want.
All that said, price being paid is indeed a factor in food quantity planning as well as the HOW its going to be served.
Again as said, these things are up to you to explain to the client, so you don't paint yourself into a corner.
An additional thought, Billy is correct about the incredible mess "loose" fillings make in a self serve buffet.
And "mess" equals waste. No one cares about wasting lettuce or bits of chopped tomato or spilled salad dressing, but wasted seafood, even in minimal quantities, should be avoided. Its similar to my having served Sloppy Joes a few times.
The ONLY way to do this is for the guest to bring the bun to you, and you slap their Joe-Goo on it for them.
Maximum control with minimum mess.
There Mimi, the semi-great Meezy hath spoken!