The Favor

Checking in on your pet or your plants while you're on a trip.

Factors to Consider

How much the kennel or a gardener would have cost. And if Max slept at the neighbor's, make sure he didn't damage anything. (If he did, you'll pay for repairs and cleaning, of course.)

The Least You Can Do

If you were gone for a night or the weekend, bring a nonperishable food gift from wherever you've been — a jug of maple syrup, a basket of fresh-picked apples.

If You Want to Do More

If you were gone for longer than a weekend, a good bottle of wine (meaning one that costs more than $20) or a gift certificate for a dinner out is appropriate.

The Favor

Your daughter is invited to go on a trip with her best friend's family.

Factors to Consider

How long the vacation was, how much supervision your kid needed, and how much the parents shelled out for incidental expenses (and travel expenses, if they insisted on paying them).

The Least You Can Do

"Give them aspirin," says Letitia Baldrige, author of New Manners for New Times: A Complete Guide to Etiquette (Scribner, $35, www.amazon.com). Sue Fox, author of Etiquette for Dummies (Wiley, $22, www.amazon.com), suggests sending your child off with a box of candy. Afterward, send a handwritten note, and offer to take their child away, too.

If You Want to Do More

A case of wine or (for non-vegetarians) some Omaha Steaks. If you know the parents well, give them something you know they'll like — such as kitchenware or tickets to a play