I'd really like a map. Here in the Bay Area, for instance, I could pretty reasonably get to games in San Francisco, Daly City, South San Francisco, San Bruno, Millbrae, Colma, Brisbane, Pacifica, Burlingame, San Mateo, Hillsborough... all of these are with a 15-20 minute drive, but if I have to type each individual city name to check, I'm just going to give up.
Maps are also good because they help people judge more easily how difficult it is to get somewhere; a game in Berkeley may be the same distance away as one in San Mateo, but the game in Berkeley means crossing the Bay Bridge. Similarly, where I'm not likely to go more than 10-15 miles away as the crow flies due to the hassle of driving, rural users would likely be willing to drive 50 miles to a game because it's a lot faster to drive places in the country.
A map is a great idea, I'll add that to the roadmap. The In Person option does do a 20 mile radius (as the crow flies) around the city you've searched. Some others folks have mentioned wanting to adjust the radius, so I'll definitely add that in and hopefully that makes things more obvious.
Maps are also good because they help people judge more easily how difficult it is to get somewhere; a game in Berkeley may be the same distance away as one in San Mateo, but the game in Berkeley means crossing the Bay Bridge. Similarly, where I'm not likely to go more than 10-15 miles away as the crow flies due to the hassle of driving, rural users would likely be willing to drive 50 miles to a game because it's a lot faster to drive places in the country.