Oh, and don't worry about posting "too much" at THIS site! It's not possible!!! :^)

Besides, the more details you can give about what it is that you want for your family's experience with music, the better able we will be to help you find it.

For instance, you haven't mentioned whether any of the three of you has played any instrument before, or can read music. My own experience has been that I learned piano first (my parents were insistent that I take lessons as a child), which laid excellent groundwork in understanding music theory -- an invaluable tool as I learned various other instruments later on (clarinet, guitar, bass, mandolin). If your son learns guitar first, it may be more difficult for him to envision the different scales, intervals between musical notes, and so forth. Purchasing an inexpensive keyboard, and playing the notes on both instruments, might be helpful.