I am an old duff too. Been playing for better than 45 years (I am 55 myself) and also collecting guitars for quite a while. I am incredibly lucky to own many fine guitars, including several Strats and Les Pauls, a couple of 335s and a beautiful ES-175 .
My advice is to find a way to play them first - either find a friend who has one, or go to a music store and really spend some time with each the guitars you are considering. I can very strongly support the ES series from Gibson, they are tremendous guitars. A 335 style guitar (including the 339) is an extremely powerful weapon. It can play just about any style, with the possible exception of very high gain stuff like metal. (A hollow body or semi-hollow just will feed back like a howling dog at high gain volumes...).
However, a 335 is a BIG guitar. Do you own an acoustic guitar? Do you get tired playing it? Arm fatigue is really common with large body guitars. Depending on your size, your arm length, and a number of other factors, the 335 MAY be uncomfortable to play for longer periods. You dont want anything limiting your "woodshed" time. ("Where's Ian? Oh he's out in the woodshed practicing that dang geetar gain"). :-)
So - i bought 335s only because the 339 wasnt available and i am a very big guy. "Dreadnaught fatigue" is real, and applies to any large body guitar.
That being said, I would probably save my blond 335 first in a fire. Maybe 2nd, but I have better than 25 guitars, and would save the 335 if I could before all but my Suhr.
This is another good point. Newer players who havent been exposed to the guitar world for very long will only know Fender and Gibson as the "good" makers. I can tell you from personal experience and from awareness of the guitar community that many of the best players dont play either Gibson or Fender guitars. There are many other guitar companies that make stunning instruments, that rival or exceed the best guitars from either. I can vouch personally for Paul Reed Smith and more recently I have been exceptionally impressed with Suhr guitars. Be careful, each of those makers also produces a lower quality line of "import" guitars that are not the real thing so to speak. These guitars cost a small fortune, new instruments are $2500 and up, but you are almost always safe buying used hi end guitars.
Drop me a PM if you have any more questions. I am always glad to help a fellow old guy guitar player! Gotta stick together agin all the young whippersnappers!
HTH
Joe