I had great luck with an airbnb rental in Paris. Nice apartment on Ile de la Cite with a view of the Seine from the balcony for much less than the cost of a small hotel room. It was six floors up in a historic building.
Are the Starwood and Marriott two different Amex cards? Might be difficult to rack up an additional 30k points with only 6 months until the trip.
Is it a moon, or a deathstar. I don't trust the Euro's, their euro steps or, well, who are we kidding, they can't make a deathstar.