Congrats on your first camping trip with the kids! We love camping and go several times a year. Here's a list of some of our kids favorite activities:
bike riding through the campground
"decorating" our campsite and drive with chalk(just have her wash it with a bucket of water and a wash cloth)
collecting pine cones etc in a pail
digging in the dirt
searching for the world's most perfect walking stick
playing catch
water play-squirt guns
hiking (searching for animals or seeing who can find the most different kinds of trees, flowers, rocks, bugs, etc.)
Be sure to let your daughter have her own flashlight
We also always bring paper and crayons for some quiet time art projects. You can use found items for tracing.
As for bedtime, it's important to keep some of your routine the same. We usually try to bath the kids right before bed(if there aren't showers then warm some water and sponge bathe them in the tent). You should bring a favorite book for a bedtime story. We always take each child's pillow, my 4 year old has a special bear, and my 2 year old has a favorite blankie. Usually, the kids are pretty exhausted from a full day of activities. The first night can be the most difficult adjusting to a new place. A stroller is great to have for a evening walk if that helps your child fall asleep. When all else fails, you can always resort to putting them in the car and driving them around for a little while. It's not ideal, but if it works use it.
Let me know if you have any questions. Camping is a wonderful experience to give your children.
PS I wanted to add that if your daughter is out of diapers, I suggest bringing a potty chair. You can keep it at the campsite and avoid those mad dashes to the bathroom. Especially in the morning. :) I also keep some water in the tent, because my daughter tends to wake up thirsty. Anything to get a few more minutes of rest and avoid getting in and out of the tent. :)