As a watch nerd, with a penchant for automatic GMT pieces, I going to capitalise on the subtle way the OP didn't mention his budget.
Flying internationally, I find a GMT watch a great tool. I have the main watch set to my home base time, the 24hr GMT is set (obviously) to UTC, and the bezel is twisted forward or back to display my current local time.
These are my two GMTs, though n ot my pictures...
Rolex GMT Master 2C
Understated, thin, great adjustable bracelet, retains value, needs no intro...
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Newer product, Omega Seamaster Planet Ocean GMT.
Bigger at 43.5mm, exquisitely finished, tough as boots, anti reflective coating on both sides of the crystal, and a more advanced, innovative Omega in-house movement, viewable though the crystal case back.
However, it's quite tall, so depending on proportions, it may not be too subtle for your purposes.
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Both similarly priced...
However, on a far smaller budget, I wear a Seiko Monster for banging around South East Asia on my travels... I can highly recommend that for bang for buck..
Also worth looking at the IWC Spitfire Chrono, or possibly an IWC MK XII, as some lovely non-GMT auto watches.
Essentially, though, I wouldn't pay more than a couple of hundred bucks for a Quartz watch, nor would I go over 1500 without the movement being made in-house, as opposed to mass produced units comr ETA... Which rules out Bremont, which are $50 movements in nice cases.
Sinn, who I would recomend, would fit into the sub-1500 bracket, however. Bulletproof, great value aviation watches.