This post is a bit late since we were talking about Hamiltons a while back. I realized that I still had one:
34mm case, fixed strap bars. This has been sitting around for close to two decades now and the watch is in serious need of oiling - it won't run unless you wind it up all the way, power reserve down to a little over a day, loses a couple of minutes a day or so. I don't even know if one can open the case anymore...
Worth saving, Hayward!
Classic field watch, despite the 'vintage' size.
I say get thee to a reputable watchmaker for a nice lube, slap it on the NATO of your choice, and I bet it gives you two more decades of service.
Would be a fun summer watch, if you think in those terms.