I'd like to echo what @amjt660 says about staying at separate hotels for the Paris and Disneyland parts of your visit. If you are set on staying at only one hotel I would choose one in Paris and then take the RER out to DLP for your visit. You'd be wasting a lot of time on the train otherwise.Hello
I have only been to Paris and DLP one time in 2011 so I cannot help with current schedules and best transportation
But I am struggling with your plan to sleep all 7 nights near DLP but only go there for 2 days.
If you have 5 day trips to Paris (or surrounding areas) you are spending approx 1.5-2 hours a day on a train getting to your destination
I would consider a Paris hotel for the first 4-5 nights and then finish the trip at the Marriott near DLP
You will get more time to sight see this way
Just my 2 cents