hey, if I were you, I wouldn't get a travel guitar per se. Generally those, like the martin backpacker aren't much in the way of sound quality. For a smaller size, my recommendation would definitely be a Baby Taylor. They sound very awesome, especially for the size. I know a lot of guitarists that like them just because they sound cool and are easy to play. Great guitar to learn on, not too expensive, and great for travel. I don't know much about the yamaha, but I would suggest away from it. If you get into guitar much at all, you're going to eventually want an acoustic-electric. For a little more money, I like lower end Taylors and the Dean exotica line. I own both, and think they sound great. Grab a friend who plays and go try them out, cause if you have an ear for it, you can get a low end name brand guitar that sounds as good as the high end ones. When I bought my Taylor, I literally tried like a hundred guitars until I found the one that had the 'ahh' moment... it just happened to be a low end one. But swing by a guitarcenter if you can and check one of these out, I think you'll like it:
but go used if at all possible, cosmetic flaws just give character to acoustics and age makes them sound better.
I've played guitar for 9+ years and have built and intensively studied guitars for quite some time.