Definitely do things you enjoy. Travel, read, learn a new skill. If your app is lacking in an area (volunteering, shadowing, etc) work on building those areas. I would also recommend trying to get a part-time job, medically-related or not. I've been able to work full-time during my gap year and have a decent savings built up. Although it's a drop in the bucket compared to the cost of school, I feel much more secure knowing that I have a safety net if I need it. Plus, at least in my experience, adcoms seem to like applicants with "real world" work experience.