If you are in the Magic or Dreams tower the quickest way is to walk under the sorcerer's hat through Downtown Disney to the parks. If you are in the Wonder tower, the quickest way is to walk across the street through the Grand Californian and use the private entrance there to go to DCA, or use the Downtown Disney exit to get to Disneyland.
If you are in the Magic or Dreams tower the quickest way is to walk under the sorcerer's hat through Downtown Disney to the parks. If you are in the Wonder tower, the quickest way is to walk across the street through the Grand Californian and use the private entrance there to go to DCA, or use the Downtown Disney exit to get to Disneyland.
This is quick & dirty from an old aerial I have. When you're in the Wonder tower (old Bonita tower), you can walk across the street, cut through the GCH lobby, and either enter DCA through the private entrance, or go through the courtyard to the Downtown Disney entrance. I have another aerial that shows where these entrances are at the GCH.
This saves time from going through the entire Downtown Disney