There is nothing wrong with waiting at home until the water breaks. However, you should then be prepared to birth unassisted, which I have done twice (my only vaginal births). The first time, the water broke about 15 min before the baby was born. The second time, the baby was born in an intact bag. http://www.unassistedchildbirth.org
Possible complications of artificially rupturing the bag are more pain, baby can't move into a better position for birthing, greater risk of infection, and greater risk of cord prolapse. http://www.pregnancy.org/article.php?sid=1529
I have heard many stories of AROM being performed without permission, so if you don't want it (or pitocin or anything they don't make you sign a consent form for), make it clear as soon as you arrive at your room, before your first vaginal exam, that you don't consent.