I recently returned from two weeks at HHV. I was not bored, but then I went to do a lot of nothing, along with reading and walking. One advantage of Waikiki is being able to walk to dozens of restaurants and stores, as well as The Bus and shopping shuttles, so I don't have to rent a car. I like Oahu (have been all over the island and seen about everything). For me it's a cheap vacation (with Hilton timeshare points, United miles, and not paying for a car).

I've also been to the other three main islands, mostly for two weeks on one island at a time. Each is a different experience, and each has advantages and disadvantages. Don't let the colleagues ruin what you've planned; it'll be a great vacation.