October is a great time to visit the park. I have always visited at the end of October. The only downfall is that you won't see as much water from the waterfalls as you do in the spring/summer but you see all of the fall colors. The temps may be cool at night and early morning but it still warms up during the day. We camped at Indian Flat (private) campground in El Portal because it is fairly close to the south gate. The park is not fancy and is all dirt but it is convenient. Yosemite is always busy but not as much as in the summer. There are plenty of short hikes. Also it is a great place to ride a bicycle if you have them. Enjoy your trip.