Geo Load Balancing Via Timing Connections

I'm working on a script to help users get routed to the nearest, fastest server for the best ping. I'm in 2 datacenters, one on the east and one one the west coast of the US.

I've looked at some of the geo lookup programs based on IP, but they either seem inaccurate or expensive.. and just downright difficult to use.

I found out that some geo load balancers use the connection speed to figure out the best route. So, I'm trying to think of a way of timing the users connection from multiple server locations.

Has anyone here done that sort of thing before? Any suggestions on how to best do that?

Two completely different methods I've considered:

1. putting 2 images on a web page, and using javascript to time the loading of them.
2. pinging the user IP from each coast and seeing which is fastest. (Is there a lighter way than ping? )