Other hotels I thought about, and then saw while walking along the beach....
The Bahia Mar looked tempting.
The Hilton Marina is still on 17th but really close in to the water.
The Westin on the beach looked nice. On the map it looks far away but if you're willing to take taxis nothing is too far away, in the beach/cruiseport/airport area.
If you're interested in the beach, since you have a 2 night stay, stay on the beach. If you're just wanting a hotel, go with the 17th street ones if the price is better. And on your way to your cruise embarkation morning, if it's a day with a lot of ships embarking (check out cruisett.com for ports and what ships are there), even if your hotel has a shuttle, consider taking a taxi. We waited and waited and waited in the October humidity for a shuttle going to Vision, when there were two big Carnival and I think another (but bigger) Royal ship in port. We'd already paid Embassy for the shuttle, but wished we hadn't, so we could just catch a faster (and cheaper for the 3 of us) taxi!