I've been treating ESP as if the Level determined how far you can sense, but that's not how it is in the rules--it just talks about your ability to perceive detail.
(Unless it's in the clarifications.)
Anyway, in the comics, it seems to me, ESP is usually a plot device rather than a tool. (Though there is sometimes a nebulous concept of "too far.")
But I have a player who is using it as a tool. I don't particularly want to stop him--his uses make sense, and range has been a nice control.
What have you guys done?