What does a week in Europe cost?

— -- A reader recently posed a simple question—with a complicated answer:

"How much does a week-long vacation to Europe cost?"

The wiseguy answer would be the same as in the old joke about consultants. Client's question: "How much is two plus two?" Consultant's answer: "How much do you want it to be?" Actually, that answer has more validity in the travel context than in business—variations are tremendous. But we can at least zero in on some lower limits.

One-city trip

One of the two least expensive options for a one-week European trip to stay in just one major city. Then, you only costs are round-trip airfare, hotel accommodations, meals, local transportation, sightseeing and admissions, and incidentals. Let's look at a trip with seven nights in Europe. (A tour operator would call it eight days and would count the overnight flight to Europe as one of the tour's nights, but in practice, you lose at least a half day on your arrival and your departure days.)

• Airfare, of course, depends on your origin, destination, and season of travel. If we assume a trip in June, currently quoted round-trip fares range from about $850 from Boston to London to about $1,150 from San Francisco to Rome. You may find the usual fare quirks—you could knock $150 off the Boston-London fare, for example, by flying an extra three hours and connecting in Washington. And future "sales" could knock $100 to $200 off those rates. Same goes for traveling in spring or fall.

• Hotel costs obviously depend on your preferred level of comfort. You can still find plenty of acceptable, if basic, hotels and B&Bs in most European capitals for under $75 per night, double occupancy, including taxes. Reasonably comfortable hotels are available for around $100 a night in many cities, but they're a bit more in London. At the low end, you'd be looking at around $600 for seven nights. Consider air/hotel packages from the big online agencies such as Expedia, Orbitz, or Travelocity, which often add to less than individual bookings. For bottom pricing in a few big cities, try Hotwire or Priceline: Hotwire, for example, is quoting rates for three-star hotels well under $100 a night in London.