My wife and I are admittedly mass transit rubes. We grew up in Los Angeles where mass transit went to die and then moved to a small town in New Mexico where it's not really required because the town is 7 miles from stem to stern.
We are, after 40 years, real estate and neighborhood experts but we got a real modern city lesson from one of our daughters and her husband when we were advising them on a home purchase last year. The number one deal breaker for them was distance to a DC metro station. After several attempts at recommending based on neighborhood, good bones, etc, I finally added the Google metro map to my list of criteria.
What we found was a great little neighborhood just outside DC that met all of our criteria for value and a reasonable walk to the nearest stop. What sealed the deal was a new metro line with a stop that will be less than a 1/4 mile from the house they chose. No condos yet but we'll have to see what happens in the future.
Rule #1, Don't lose money. Rule #2, read rule #1. - WB.