At L'Espalier in Boston, departing guests receive small bags of macaroons. At the French Laundry in Yountville, Calif., it's shortbread cookies and boxes of chocolate. Relatively few restaurants have specially prepared favors to offer, but people frequently leave all kinds of restaurants with souvenirs that influence their final impressions -- their leftovers.

It's easy to see why sending someone home with a bag of signature cookies could win a restaurant extra affection. Yet few restaurants seem to realize that the way leftovers are packaged and handled has a significant effect on a guest's experience.

Unless someone requests otherwise, servers in full-service restaurants should pack up leftovers for the diner, preferably away from the table. One of the primary joys of dining out is avoiding the clearing up. Watching someone scrape plates isn't much more fun than doing it yourself.

Most fine dining restaurants in Pittsburgh do package leftovers out of sight, but that doesn't guarantee an elegant package. A plastic grocery bag and styrofoam containers look out of place in an elegant restaurant, especially when they're plunked on the table while a group is lingering over dessert.

Styrofoam containers may be cheap, but they're also ugly, annoying to carry and likely to spill. Some restaurants take care of the latter by wrapping the containers in swaths of plastic wrap, something I have never seen outside Pittsburgh. Surely it would be easier to use a more stable, sturdy container in the first place.

Many U.S. cities, including Los Angeles, San Francisco and Seattle, have banned styrofoam containers in restaurants because of their environmental impact. It's especially off-putting when a restaurant that emphasizes sustainable food presents leftover grass-fed beef in a styrofoam container.

Even if the negative effect of poor packaging is slight, restaurants are missing out on an opportunity to leave diners with a positive impression.

Restaurants can go above and beyond in a number of ways. At Willow in Ohio Township, servers mark to-go boxes with the name of the dish and the date it was consumed.

At Lidia's Pittsburgh, in the Strip District, boxes are placed in attractive brown paper shopping bags emblazoned with the name of the restaurant. People may even reuse these bags, providing free advertising for the restaurant.

Cioppino, also in the Strip District, gives guests a coat check tag so they can claim leftovers on their way out.

These extra touches may be more expensive, but they are all ways a restaurant can distinguish itself in the eyes of a customer.

Diners can help make these choices more affordable for restaurants by asking for leftovers only when it's worthwhile. Not all leftovers are created equal. You paid for dinner and are thus entitled to the dinner rolls and that 2-ounce portion of pasta, but is it really worth taking them home?

Try to take home only food that you have a plan for eating. If you're not going to have it for lunch or dinner the next day, you're likely to forget it's in the fridge at all. Remember to think about food safety. If food went unrefrigerated for more than a couple of hours, it's safest to heat it to 165 degrees before eating it. Remember, not all leftovers are created equal. Don't bother taking home:

• Any food you didn't love the first time.

• Most fish -- It will become mushy and fishy tasting after even one night in the refrigerator.

• Salads with dressing.

• Raw meat or fish dishes -- risk of contamination is dangerously high.

Yet some dishes are perfect as leftovers -- think roast turkey -- and having them can inspire wonderful second-day meals, which really does add value to the original dish. It's always worth taking:

• Leftover steamed rice for making fried rice.

• Roasted meats or vegetables, which can be turned into wonderful salads or casseroles or used as filling for omelets or quiches.

• Stewed or braised dishes, which may taste even better the second day.

• Most pasta dishes.

Having a plan for using leftovers also can be good for your health. If you're thinking about the delicious fried rice you're going to make for dinner tomorrow night, you'll be less likely to consume a giant bowl of it the first night.

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