I love seeing terns, gulls, waders and other sea birds exhibited, but at least in north america they are fairly uncommon. In your opinion, is there a reason for this, or are they just unavailable.
I'm not sure, but I suspect the more pelagic species don't breed too well in captivity.
In Europe, waders are common in zoos - species like redshanks, ruffs, avocets, oystercatchers and stilts are aviary standards. Gulls and terns rather less so, with the possible exception of the beautiful Inca Tern. Living Coasts, Walsrode and Tierpark Berlin all have good larid collections - although the Tierpark's are off show at the moment as their magnificent gull aviary is being renovated.