Since you are wanting to fly to Hawaii and stay in the Hilton...there are a couple options that I would consider.

Hilton Points (you could probably apply for all of these at the same time):

2x Hilton Citi Cards using the multi browser trick (50k and 40k apps): 90k total points
2x Hawaiian Airlines cards (1 from BoA and 1 from BoH): 70k Hawaiian Airline miles which you would then transfer 1:2 to Hilton for 140k points.
1x Hilton Amex card: 60k points

This would give you a total of 290k Hilton points. There is also a Virgin Atlantic card that you could sign up for which gives ~50k miles on signup which can then be xfered to Hilton for another 100k points.

As an alternative to signing up for the 2 Citi cards, you might consider doing the Citi Thank You Premier card, which is similar to Sapphire and has a $500 bonus. That card bundled along with the Chase Ink Bold card (which you should be able to get by closing out one of your current Chase cards), would yield $1000 signup bonus total which would then be good for roughly $1250 worth of travel. If you factor in the Sapphire card which you already have, that would be $1875 worth of travel.

For the first class trip to Hawaii, you could again sign up for the 2 Hawaiian Airlines cards and use the miles to fly, but then you wouldn't be able to transfer to Hilton.

There are numerous other airline credit card offers out there right now, but I don't think any of them would give you enough miles to fly 4 people first class.