I just returned from a 5 night stay at the Marriott Grand Flora. I used 160,000 points, booked it 2 weeks ahead on the Marriott site and had no problems doing that. Just lucky I guess! But if you're pining away for this hotel, let me offer a quick sanity check. As others have mentioned elsewhere on this forum, it's a good hotel in a great location. It's NOT a great hotel, just a good one.

There's no lounge and while the free breakfast on the top floor has a lot of variety, the service is slow and unattentive, e.g. trying to get two cappucinos in 30 minutes is a struggle. The view is of Rome's skyline - a bunch of low-rise apartments and office buildings with dozens of antennas mounted in every direction on their roofs. On the days we woke early, the outdoor tables were okay, but if you arrive for breakfast much after 9am, the hot sun will drive you inside in minutes.

I got a platinum upgrade to a 4th floor view room, which had a sideways view of the Aurelian Wall and nothing else. The garbage trucks outside directly underneath our window did their work late at night, every night. The room size was average by European standards and small by US standards. The air conditioner struggled mightily to keep the room at a halfway decent temperature, but mostly lost that battle during the afternoon. The paint, furnishings and furniture were very dated. The staff was good and helpful at the front desk, but sometimes painfully slow.

I know the other options within Marriott in Rome are limited, but other chains may be a viable consideration. This hotel is an A+ for location but just a C+ for the property itself.