You will love the Courtyard Marriott. The water park is a fabulous way to spend some of your afternoons if they are really warm.
The hotel also offered us lots and lots of food options. And even special seating areas in the evenings to watch the fireworks around a fire if you aren't staying in the park for that.
The walking distance to the gates is actually closer from the Courtyard Marriott than it is from DLH.
To be honest, I think ten days at the two Disney parks is a TON of time. Even taking afternoon breaks at the hotel water park and/or pools, you could do it all in 6 - 7 days and then some. We just finished our fifth trip in ten years and we found we were able to do everything we wanted in a day and a half! Now, that's considering the fact that after so many visits we know what we can skip. But still, in 3 days we did 31 rides, the Frozen show, some time at the water park, and siestas every afternoon!
Have you considered popping over to Universal Studios and/or Harry Potter too?