Hawaii is amazing - all of it. Just returned from 6 nights in Oahu. We actually really like Oahu and did not find it "crowded" on the beaches. I would not like 3 islands in 2 weeks, for me, part of the wonder of Hawaii is relaxing and packing, unpacking, airport security is not fun. I would do two islands in the 2 weeks.

I think next time we go we are going to try to do 5 nights in Oahu and 5 or 6 nights on the Big Island or Kauai.