We are looking to travel to Hawaii in the next year or two. We live on the east coast near Philly so I know the travel days will be long. Just looking for advice on how best to make the trip, better to take two days to travel? Also what's a good time frame for a vacation there? Our preference is probably to stay on one island as we need to get some r&r while on vacation along with sightseeing.
I'd suggest you decide which island(s) you want to see, and make plans accordingly. Some carriers (Alaska Air, for one) fly directly into each of the four main islands. Other carriers, (Hawaiian Airlines) fly into Honolulu or Maui directly, but most flights route through Honolulu. Interisland travel within Hawaii will add time to your travel days, and an additional ~$200 r/t each, if you're scheduling a separate inter island trip. FYI, I just checked Hawaiian Airlines, and they fly nonstop from JFK to Honolulu. I know a hop from Philadelphia to JFK wouldn't be that hard to do, and it may help ease the travel burden a bit. There may be other options, too, so you'd have to check around. The lowest price isn't always the best deal - time and itinerary are important too.
There are many threads here about which island(s) to visit, and why they're each interesting. Searching for things you want to do in Hawaii will give you some great answers to think about. It all depends on how you want to spend your time. If you want to see historical things, Oahu has Pearl Harbor, Waikiki, Diamond Head, and such. In Honolulu, it's crowded, and traffic can be a mess. But if you're traveling with kids who want Disney, the Aulani resort is on that island. Oahu has great beaches on the windward side of the island, which happens to be away from the crowds on the leeward side of the island. It's fairly easy to get away from the crowds and have an awesome vacation, if you plan accordingly.
Kauai is the least crowded of the four main islands, has great beaches, and a very laid-back atmosphere. You could unpack there and relax for the whole trip, but you'd basically be doing just that - relaxing, since there isn't a lot of nightlife or variety of activities. Hiking, biking, beach time, and relaxing are the main things you'll find on Kauai.
Maui has a whole lot to see and do, has great beaches, but can also be crowded, busy, and expensive. There is plenty to keep a family occupied, as long as you know what you want to do with your time.
The Big Island of Hawaii is very large, so getting around takes time. But that's where the active volcanoes are. If you want to see a volcano in action, you have to go to the BI. Sandy beaches are harder to find, since the island is geologically younger, and Mother Nature hasn't had a lot of time to break down rocks and coral into sandy beaches.
My suggestion for a first trip would be to try to fly nonstop into Honolulu, (sleep on the plane), and spend a few days. See Pearl Harbor, Diamond Head, and the classic Hawaiian sites, and get your Hawaiian time legs under you. Then move to a second island, and spent the bulk of your vacation there. Enjoy it for all its worth, then fly home by whatever way works best for you (another nonstop to JFK, or something with a stop along the way.) There is no easy way to get there from where you are, so I say rip off the bandaid and get there as quickly as you can. Layovers only delay the goal.
Good luck!
Dave