If you don't have enough points for aspirational stays, I would focus on Priceline.

European cities tend to have far fewer rebid zones than a lot of big US cities do (Dallas and LA, for example, are a bidder's dream) but you can still do pretty well.

I would suggest focusing on 3.5* and 4* properties on Priceline to ensure that you don't get stuck with a bad place for your honeymoon.

Alternatively, if you don't want to take the risk on Priceline, you can use Hotwire and use BetterBidding.com to get a good feel for which property you are getting.

Please take what I say with a grain of salt as you are talking to a guy who books 20 - 30 nights/year on Priceline but didn't use it for his own honeymoon.