(MONEY Magazine) – I've been on my share of vacations with friends and extended family and survived the most common pitfalls—like people running up the group tab at dinner with expensive wines, planned activities that I wanted no part of and living arrangements that afforded too little privacy. The topper for me was the time a vacation mate I didn't know well but had invited as part of a large group got nailed cheating in a card game with my better friends. I was stuck between their cold shoulders and my misbegotten guest for the rest of week.

Despite the obvious problems, though, lots of grown-ups still choose to vacation in packs. Why tote that baggage? Well, for one thing, traveling as part of a group can be much more economical than going as a single family. After all, the cost of renting a beachfront house on Cape Cod or a villa in Tuscany costs a lot less split three or four ways than one. Vacationing with other couples or families could be the key to taking the trip you really want instead of the one you can afford. "It is a phenomenal way to save money," says Erik Torkells, editor of Budget Travel.

Besides, when all goes well, travel with friends can make a trip more fun. Just make sure you take the following precautions to save the most money and keep your group vacation... a vacation:

TALK ABOUT COSTS IN ADVANCE

Plan your trip with input from everyone you're traveling with, clearly spelling out the costs and obligations of each person or family. You should have a sense of everyone's budget up front, what's important to them and what isn't, and what they're eager (or at least willing) to spend money on and what they'd rather skip. Will the group cook in? Set up a rotation and food budget. Will you eat out? Choose the restaurants (and wine budget) ahead of time. Who gets the master bedroom? Certainly not whoever arrives first; leave it as a reward for the group organizer, draw straws or ask someone to pay a bit more for it. And don't make any assumptions about other people's ability or willingness to pay. Even though your friends may be loaded, they probably do not like to spend money any more than you do.

Finally, be prepared to let some disgruntlements over money slide. "Things won't always even out," says Nadine Nardi Davidson, author of Travel with Others Without Wishing They'd Stayed Home. "If you're the kind of person who doesn't like to spend a penny more than you receive, don't take a vacation with friends." Or do it at an all-inclusive resort, where splitting the dinner check fairly won't be an issue.

CREATE AN EXIT PLAN

To avoid getting stuck paying the share of a friend who has a last-minute change of heart, draw up a payment schedule with three dates: one for when the deposit is due, a second date giving members of the group a last chance to opt out and a final date when everyone has to pay in full. The opt-out date is key yet often overlooked. After this point you should be on the hook for any money already paid and for a portion—possibly all—of your share of the fixed costs. That's only fair. When one person backs out late in the game it drives the cost of, say, a beach-house rental much higher for everyone else.

CUT A GROUP RATE

Group rates won't apply if you're renting a house or taking just a couple of rooms at a resort. But if you're reserving eight or more rooms at a large hotel or as few as four at a small inn, says Torkells, a group discount can cut the bill by as much as 25%, depending on how many rooms you take. Appoint one person to work with the group-sales department rather than booking online or individually. And be sure to ask about other available perks. Among some of the more common offerings: a suite at regular room rates so the group has a place to gather, discounts on tours or entry to area attractions, a free spa visit, complimentary breakfast or a gift certificate to the hotel souvenir shop.

WORK IT OUT

No matter how well you plan, issues will come up once the trip is under way. Maybe a member of your entourage invites Uncle Lou to stop in for a few days, a neat freak insists on a midpoint cleaning service you feel isn't worth the money or someone abuses the pooled money in the cookie jar designated for incidentals. You're friends, talk it out.

Hey, at least they're not cheating at cards. If tensions run irreversibly high, try to salvage your vacation by carving out more alone time. "If all else fails," says Lynn Hayes, editor of familytravel.com, "get an urgent call from the office and leave." Yes, you'd be liable for your share of the fixed costs. But forfeiting a day or two of vacation—and eating the expense—may be a small price to pay to preserve a relationship you truly valued before the travel nightmare began.

One vacation mate turned out to be a card cheat. Still, the pros of traveling with friends—big savings, more fun—outweigh the cons.

Dan Kadlec is co-author of The Power Years, a guide for boomers. E-mail him at boom_years@moneymail.com.