Think about why you are considering a vacation to Europe. To take in famous sights like the Eiffel Tower or the Colosseum? To enjoy authentic local cuisine? To stroll through charming neighborhoods and soak up the atmosphere?
Whatever your reason, we feel pretty confident it isn't “to spend as much time sitting in a taxi or on a subway car as possible.” People often use “vacation” and “travel” interchangeably, but the act of traveling is rarely the highlight of a trip. Keep that in mind when choosing a hotel. Hotels might be cheaper in, say, the suburbs of Paris than in the Latin Quarter or the Marais in the city center, but your vacation time is precious. If you have a long subway ride every single day to reach the things you actually want to see, you'll be adding a tiring and possibly stressful element to your trip that doesn't need to be there.
Price matters, of course. But instead of thinking only about a hotel's price, think about overall value. If a hotel is less expensive but is in a less convenient location, then that may not be a good value.