We did 3 nights on Maui before 6 nights at Aulani. We also spent 3 nights in Waikiki and 3 nights on Kauai. Of all the places we stayed and visited, Maui was my least favorite - I mean, we still loved it, but it wouldn't be on the top of my list to return to if we ever go back.
The island was a mix of natural beauty and commercialization, so it felt similar to Oahu in that regard. Kauai felt the most remote and exotic and I imagine Big Island would feel that way too. The weather on Maui was also quite windy while we were there in September (end of summer), to the point where we couldn't lay on the beach because of sand blowing in our faces. The waves on the Kaanapali side were also really high and rough.
Ironically, even though Maui was our least favorite stop, the Westin Maui was probably our favorite resort we stayed at on our trip. It was on Kaanapali Beach and at the time, they had free shuttle service into Lahaina so we didn't rent a car. Small-ish resort, but with an awesome pool, waterslide, and right next door to Whaler's Village for additional dining and shopping. Also, two of the highest rated luaus in Hawaii are both on Maui in Lahaina - Old Lahaina Luau and Feast at Lele. We did Feast and it was awesome. I definitely recommend doing one of those if you plan to do a luau at all on your trip, and I think an evening for dinner on Front St Lahaina is a must too. Loved the banyan tree, and we saw a beautiful sunset on the water, enjoyed watching the cruise ships, and had the best shave ice we had on the whole trip on Front St.
We toyed with the idea of doing Road to Hana, but it is a full day and we didn't feel like we had that kind of time to spare. Its often recommended to do this on a tour rather than trying to drive yourself because it is some dicey driving and I can't imagine the driver can actually enjoy the scenery. I believe some rental car companies also prohibit their cars being driven in certain spots because of the inherent risk.
As far as timing, 10 days on Oahu doesn't seem too much to me. We spent 9 nights on Oahu in total. We agree with Kevin and John from the Dis Unplugged podcast that Oahu is the best choice if your time is limited because it offers a little bit of everything - natural beauty, shopping, culture, history, nightlife. The other islands of Hawaii have elements of this, but Oahu is a "one stop shop" so to speak. I think 10 days there gives you enough time to visit the main "tourist" things you'd want to see, with time to enjoy the amenities of Aulani. We were satisfied with 3 nights on Maui, but it totally depends which activities and sightseeing are most important to you.