to reduce the "harried" feeling, do the Big Island at the end of your trip and return home from there.
Volcano sightseeing:
https://www.tripadvisor.com/Attracti...ii_Hawaii.html
Your daughter can swim with dolphins at the Kahala Hotel.
Best time to buy Interisland tickets is the present. They only get more expensive. Fly Hawaiian Airlines for the best on-time performance and reliability.