The Heavy Guitars
One more thing to consider when choosing your guitar could be the over-all size and, or the weight of the instrument. Some of these axes can be quite a hefty handful, most notably the Gibson Les Paul. Les Paul himself was quoted stating; "They had to add a whole new wing onto the Mayo Clinic" (just to handle the back problems associated with his guitars.) Plenty of guitarists are well aware of this scenario and choose to suffer through it because the tone they get with their guitar is worth the price of whatever pain they may have to endure.
Large guitars like Dreadnoughts and some of the Jumbos can ask a lot of your shoulders, particularly if you're of small frame, placing the shoulder of your strumming hand higher than that of your picking hand. Your ability to reach the bass end of the neck without being hyper extended is also critical. Your arm should be relaxed at the elbow in all positions.
Many of us, myself included, prefer smaller bodied guitars like Concert size Classical guitars or Auditoriums or the more familiar Martin sizes of "O", "OO", "OOO", and "OM" or Single Ought, Double Ought, Triple Ought, and Orchestra Models respectively. Generally it is evident that the vast majority of finger style players prefer the smaller bodies, revered for their string to string balance as well as comfort. While strummers tend to enjoy the added bass response found in the larger guitars, namely the Dreadnought and Jumbo body sizes.
So if there is any question of the integrity of your lower back, shoulders, hips, knees, etc. or just your own personal ergonomics and comfort, you just might want to keep in mind the issue of size, weight and gravity. Whatever the case , try to make sure you are comfortable holding and playing the guitar and by all means "pic long & prosper" - Lightning Joe