This was a Hilton until 7/31/06 so I guess there isn't much about it on the website yet. I have a stay booked there at the end of Sept. so I'll report when I get back.
I don't believe you need a car there since the location is close to Duval Street where all the action is. However, if you don't have a car I think 9 days may be a little too much. I would like to see other parts of Florida if I had that much time. But that is just my opinion. I have never been there before so I might change my mind after my stay and think 9 days is not enough.
There used to be a boat to take you to Sunset Key Resort for a fee of $10 per person when the Hilton owned the property. I don't know if that is still available. However, I don't think there is much of a beach in key west especially at the resort. Sunset Key might be a different story so I'll let the others report what they have experienced.
We're renting a car and driving from Miami. The airfare was much cheaper than into Key West and I love the drive. Hope some of this info helps.