I think giving the note is being a considerate neighbor, and is something I'd appreciate. I know you said your husband is insistent about giving the gift cards, which is sweet, however it may put unintentional stress on the neighbors, who may feel that they then need to reciprocate in kind should they ever have work done, even though from how you seem in your posts I would guess that you would have no such expectation. I say just give what you would like to be given should roles be reversed, in this case, the consideration of a note.
Edit: Should unforeseen inconveniences occur, an after the fact gift (fruit, as mentioned above?), as a "Whew, thank you for your patience!", seems fitting. Something about a gift card, with a clear dollar amount, has me envisioning a group of well-meaning neighbors stressing over what the $ is for a driveway resurfacing ($5 coffee card?), vs. reflooring ($15 movie theater card?), vs. a whole house remodel (all expense paid weekend in Hawaii!)