Dear Etiquetteer: Can you tell me whether you think people who have been good guests at a dinner party or cocktail party (separate answers I think) - brought a hostess gift, behaved well, etc. - should also email or call the next day to say thanks? If they don't, were they unhappy with the party?
When a Lovely Note of Thanks has not been received, it's always more charitable to assume Incompetence rather than Malice. Possibly your guests were taken ill, swept up in current events, anxious at the thought of finding something original to say about your party (which is completely unnecessary), or just too lazy to find your zip code. Regardless, their failure to express gratitude for your hospitality is no reflection on the hospitality you provided.
Etiquetteer may be the Lone Holdout in considering the Lovely Note more important than the hostess gift, but the expression of thanks afterward means ten times as much as the "payment for services rendered" sometimes implied by that bottle of wine. Few things reassure a host or hostess as much as the confirmation from guests of a "job well done," that one's efforts have not only been recognized, but appreciated. Too many people, Etiquetteer would suggest, feel daunted by the need to express themselves originally. But writing a Lovely Note certainly doesn't take as much effort as picking out a bottle of wine. (Etiquetteer can just hear the oenophiles shuddering as they read this.)
You are more accommodating than Etiquetteer is in terms of how you'd allow these Lovely Notes to be delivered, suggesting email and telephone as options without even considering a handwritten note - which even today Etiquetteer is loath to refer to as "old-fashioned." Communications unavoidably evolve with technology; this is not necessarily bad, but it's made many people careless. While it was once the only way to communicate at all, now - with the near-universal adoption of the Internet - handwritten correspondence now signifies a special effort to express sincerity and appreciation. This is why Etiquetteer continues to think it's the best way to convey thanks for hospitality received.
Etiquetteer hopes that you will not let the neglect of your guests cause you further anxiety, and that you'll set them a good example with your own Lovely Notes after they entertain you in turn.