keeping my roads as well. I've found there are two main thoroughfares that my gamblers take to get to the other side of town where the casino is at, so it's pretty simple to scan those roads and get 'em as they shuffle along.
with neighbor visits, I've found it much quicker to find three gamblers to tap in neighbor towns with extensive roads... the ones who only have concrete and either no roads or a small strip where everyone gathers have been more difficult to find and/or tap. Just my 2 cents... your experience may vary :P