Fairway's "healthy" tuna salad is delish! They say it's "healthy" because it's made with tofu mayo... the whole thing really works because the mayo doesn't overpower their mix of tuna, carrots and herbs. yummy.
I rarely order plain tuna salad (not a veggie person) but I love tuna salad sandwich. For the lighter versions (with less mayo but tuna in olive oil), I like the ones at Bouchon Bakery and wichcraft. Eisenberg got the classic American style right in a hefty size!