Depending on where you are in DTD, it is no more than 10 minutes. The corridor of DTD shops/eateries starts right outside of DL and DCA and leads straight to the DLH and ends there. The Grand is about half way up on the left. It is very close. Have a great trip.
The Disneyland Hotel is at the one end of Downtown Disney. Actually the opposite end from the main entrance to the parks. The Monorail is a few store fronts away from the hotel end. If you have a map with DTD the hotel is just past ESPN Zone. http://www.geocities.com/maryjomw/dlhotelaerial.htm has an aerial view of the hotel. If you click on the map labels will appear & you can see the building on the right is the ESPN Zone. I found this off of the links on here under "Maps and Aerial Shots of the Disneyland Resort, Los Angeles, Etc. **"
Hope that helps!
Sue