I stayed at Blue Tree a couple of years ago, and it is very convienient to DTD, just a couple of minutes drive. At the time, they had a shuttle van that went over in the morning, and did a pick up later on; it didn't tun all day, and you had to work by their schedule. The management has since been taken over by Westgate, so things may have changed.
When we were there, we had a car so we didn't use their shuttle at all.
With ParkHoppers you will still have to pay to get into the Parks parking lots. You can use the DTD transprotation with PH passes, but I don't think the schedule is all that great, especially in the morning. Since you're going to need a shuttle or a car to get to DTD, just take it into the parks.
Try getting a full size van, if possible.
Alamo has some special rates out now, I just got an email today about them.