How do you use your GMT?

I am eagerly awaiting a 6117-6410 Navigator Timer. As with so many other vintage Seiko designs (6309-704x,6105-811x,6139-600x) this one started as "Oh, that's interesting but whatever..." to " I MUST HAVE IT!". I may be starting down a slippery slope of 4th hand ruination as there are several World Timers that are also kind of stimulating dopamine production. I am a Seikoholic looking for a fix...

I have researched ad nausea and I feel that I have a comprehensive understanding as to how the 4th hand and 24 hour ring in a 6117 are used. What I was wondering was how do my addicted brethren use theirs? I will probably set the 2nd time zone to US pacific. I am on the east coast and have a sister on the west coast with whom I converse almost daily. I do not need a device to calculate a 3hr time shift but what the heck...

Do you track GMT? Track the time zone of a loved one? Every actually calculate longitude while at sea?

screen caps of seller's pics (and an original H link! yippee!!)...






EDIT: Watch arrived today (06/04/10). Much better than the eBay pics. Seems to be all original, works splendidly. Eventually a service, gaskets, lume, maybe crystal...but for now she's good to go as is!