Unity 3d Networking Local Search

Note: I Am Using Javascript And Am Designing this Game For The Computer And Possibly The Xbox360 And PS3

Hi, I've Been Trying To Network An FPS Game And While I Was BrainStorming I Thought That Players Would "Lag" A lot if They Were Playing With Players From Another Continent So I Was Wondering If I Would Be Able To Access The location They Are At And Let Them Choose A Parameter Like Within 80 Miles Or Will I Have To Do It The Very Long Way...

Ex. of Very Long Way.

Choose Continent(7 Options)

Choose Country(Many Options)

Choose Nearest Major City(Too Many Options)

I Also Thought Of Doing It An Easier Way But I'd Still Prefer The First Way If Possible:

Easier Way:

Enter Latitude(Possibly Not Known And They Might Not Know How Or Want To Search The Internet For it)

Enter Longitude(Same Problem)

I'll Appreciate Any Good Answers I Get, Thanks