
Hi Peter
You can't go wrong with the look and the comfort of Nato strap in Nylon and leather.
Here is the basic black. It can be worn form or casual. You can try different color combos based on you mood. Buy three or four straps to start you off and before you know it you will have a dozen.
Basic black.


Sorry no GMT nato pics. Vlad has some.
Bill
and also how wild you want to go...
I am a strap man...and like me you can even have several to switch and express the different personalities of your watch. In the case of a GMT like this one, it opens the most possibilities but makes it also difficult to achieve a good result.
Natos are fun, cheap and exist is a variety of colors so you can really play and match the parts you want on the watch, the dial, the indexes, the bezel, the GMT hand, or even several at a time. Here is an example on a GMT (not Rolex sorry)

Then if you go into custom made straps, you can put some thought and have fun. The watch makes it somewhat hard as it is multi colored and the bezel is faded. I would suggest working with a blue leather, if you can find some which is mat or aged, or nubucked to match the blue fading of the bezel, then putting a contrasted red stitching. This would give it a nice fresh colorful look for the summer. Here is an example I briefed for a watch with some similar complexities, multi color, with blue and red...(again no Rolex, sorry!)

I am happy with the result.
Matt