You are starting late ( trip is in ~ 8 months) but here is away to get 8 free hotel nights without paying any credit card annual fees.
I also believe your US Air card should have a $99 companion fare if you can't pull off the miles needed for 2 flights.
Your best bet saying you are starting from zero hotel points and have no status at any hotel is to get a Hilton Amex card for both of you and the 40,000 points that come with spending $750. Just as important is the HH Amex gives each of you access to book AXON 7 awards.
Then each of you ( you're running short on time so do it the same day) get the 50,000 point/$1000 spend Citi HH Visa. You can each get 2 of these cards every ~70 days, churning 3 cards each will cost you $3,000 in spend and bring over 150K points each.
After getting the HH AMEX and 3 Citi HH Visas and spending $3750 on the cards you each have over 190K HH points which then allows you to book an AXON 7 award which is 4 nights at a Hilton Cat 7 , each of you do this and you will have 8 nights in the same hotel , most likely not even having to change rooms
This hotel is on the beach in Hawaii and a CAT 7 so 190K for 4 nights.
http://www3.hilton.com/en/hotels/haw...VHH/index.html