I'd suggest the Peninsula too, as it's my favorite in Hong Kong. I have an upcoming stay booked there before the world tourism industry was knocked sideways by the financial crisis, and I'm paying far less than $1000 for a Harbour View Room in the tower. I've seen on their website all kinds of promotions with rates running under $500 for Deluxe rooms (city view, old building). Because service and atmosphere matter greatly to me, I'd go for the lower category of room in a higher-end hotel over a higher category in a mid-market hotel. Personal preference, but it has always served me well.

That said, if the IC is truly sold out, there must be something going on in town sucking up hotel rooms and leaving the few remaining at high rates. If that's the case, I'd suggest the OP check back as the honeymoon gets closer-- in the US, rooms sometimes get released onto the open market if demand for the big blocks of rooms reserved for whatever meeting or convention has reserved them doesn't materialize.

I'll throw out two other options not mentioned yet. First, the Excelsior, managed by the Mandarin Oriental group, is in Causeway Bay and may have rooms with at least partial harbour views in the range of the OP's budget. Second, isn't there a Renaissance or something like that in the same complex as the IC?