For those that have never been, I'd do Oahu as the first option for the obligate historical and tourist issues.
I don't especially like Oahu, but...I kinda agree with Dean here.
Pearl Harbor is on Oahu, as is Waikiki, as is Diamond Head. The North Shore is legendary surfing territory. We've been there, done that, and ain't going back, but for a first time visitor Oahu has some things other islands don't.
I agree with Maui as the best middle ground. Tons of organized, tourist activities -- bike down Haleakala (the volcano), scuba trip to Molokai, whale watching in season, Lahaina's shops and restaurants, Road to Hana, etc, etc, etc -- plus lots of golf and other diversions. WAY more to do than Oahu.
For relaxation, I'd probably go with the Big Island or Kauii.
Although Honolulu is certainly an urban area, I'd never compare it with SFO or Chicago!
I never get tired of SFO, Chicago, and NYC -- they are great cities. Honolulu is a less than charming large town with a nice beach -- doesn't begin to compare with Miami Beach...or several dozen other beach resort areas.