We thought a studio was tight for just two adults. It's smaller than a standard hotel room. You will have a queen size bed and a full size sleeper sofa that pulls out in front of the balcony door. Not much walking room when it's pulled out. You can definitely all fit, but it will be a tight squeeze, especially with luggage, etc. Might not be the most comfortable but I think I'd bite the bullet before deciding to stay elsewhere since it's only a couple days.
I agree with PPs that it's a lot of moving around for a short time. I'd scrap Turtle Bay. My original plan was to do 3 nights at Aulani and 3 nights at Turtle Bay, but we ended up canceling Turtle Bay and doing 6 nights at Aulani and I was so glad we did. Traveling around, packing up, checking in/out, etc. eats up a lot of time taking care of business. You don't get to enjoy the full extent of the resorts either.
We did 3 nights in Waikiki which would be max for me. The beach was crowded so we used the time to do most of our sightseeing and shopping. With a total of 8 nights, I would do 2 nights in Waikiki and the remaining 6 nights elsewhere on the island - Aulani or Turtle Bay or somewhere more budget friendly if need be.