We were just there and stayed at another resort that is not quite as far north as Mata Chica. The water taxi might be an expense ($5US per person 1 way unless your hotel has a different offer), and can be a timing issue. They might be able to tell you how often the ferry will run in Oct, so that you'll know how easy it will be to get into town. You might think about how much time you like to spend lounging around a resort or going on excursions, and how much time you like to spend seeing the day-to-day life of the area. We went into town every day and often twice a day to try a new restaurant, listen to music, try karaoke, etc., so the distance could be daunting. Here's a total girl tip: if you're taking the ferry, bring a hooded jacket or a hair clip, and a brush. I'm not overly concerned with my hair (don't even own hairspray), but even I would rather not sit down to a nice dinner with wind-blown knots. :-) Congratulations, and have a wonderful honeymoon!