How flexible are you with your budget for this trip. Ask yourself how much do I want to spend out of pocket. Me and wife normally settle for about 30 to 50% out of pocket. My suggestion, stick with United and try to accummulate 80K miles, then you and your wife try to apply for either a Chase Sapphire or the Citibank Thank You Premiere card, that have at least a 40K or 50K as a signup bonus. These points are worth 25% to 33% more when redeeming for airfare. The reason why I say this is because trying to redeem United miles for 4 people on one flight will kind of tough, not impossible but tough. But redeeming UA miles for two tickets and using your Chase or Citibank points to buy the other two tickets will guarantee all 4 of you will travel together on the same flight. And UA has pretty good availability to Hawaii. Better than Delta or American IMHO. Flights to Hawaii in the spring are going for about $650 right now. So 50K Sapphire or Citibank points will cover most if not all of that cost. Me and wife are going to Cancun this fall and using a combination of United miles, Citibank Thank You points, AMEX MR points, and Cap1 Miles. We are going to save approximatly $1600 on a $2600 10-day trip at an all-inclusive including a car rental. And we will still have enough points/miles leftover to take several more trips over the next couple of years.