We went through this booking rooms for a European trip next summer as a family of 4. In some cities, we were able to book an upgraded Junior Suite room for 25k-35k per night in points but have to pay a cash upgrade for the non-standard room (costing about $150 per night in USD). This got us a room with 2 queens or 2 kings and more square footage (550 SF +/-). However, there were other cities we got nowhere with Marriott and ended up booking family rooms with Hilton (for only 10k-15k per night) to get a standard size room with 2 queen beds that was 300 SF +/-.