They felt most comfortable with Jennifer McClaren, a licensed saleswoman at Keller Williams TriBeCa, who agreed to take on the challenge: As Mr. Ramsey traveled often and Ms. Ramsey was occupied with the couple’s two young sons out west, they would have to choose a place sight unseen.

They envisioned a living room big enough for the children to play in. Without a yard or a car, they figured they might be spending plenty of time indoors, at least when the weather was bad. And they hoped for a washer-dryer and an elevator.

“Those things were shot down fairly quickly,” Mr. Ramsey said.

With their budget, Ms. McClaren told them, apartments with those amenities would be one-bedrooms, if not studios, or would have serious drawbacks. “Listings that I thought would fit their budget would not fit their life,” she said. “I tried to guide them to a higher price point.”

“It was better that we had somebody who knew what to expect,” Ms. Ramsey said.

Ms. McClaren sent pictures and videos — helpfully narrated — of options on the Upper West Side and its neighbors, Morningside Heights and Manhattan Valley. Spaces often looked big in still photos, but videos were far more revealing. At a five-story walk-up building in Manhattan Valley, three two-bedrooms were vacant, all newly renovated and with plenty of stairs. The rent was $3,300 or $3,400.