Hi, Laura, To get to the Grand Floridian from Caribbean Beach you will need to transfer somewhere along the way.
One option is to be to take the bus from your resort to the Magic Kingdom. From here, walk over to the Resort Monorail which will take you to the beautiful Grand Floridian. Allow about 45 minutes - 1 hour depending on crowds.
If you take the bus to Epcot from your resort, you would need to then hop on the Grand Floridian bus (quicker than taking the monorail since you would have to switch monorails at the TTC.)
Your other option (might be a few minutes quicker) would be to take the bus to Hollywood Studios and transfer to a Grand Floridian bus.
I know it all sounds quite complicated, but it is just the resort to resort transfers that get sticky. Otherwise, it all stays pretty simple. To get ideas of routes and transportation times, go to
www.ourlaughingplace.com and scroll down to the Transportation Wizard. Choose Point A and Point B and the Wizard will calculate your routes.
Cast Members will be happy to assist you if you have any transportation questions when you get there. In no time at all, you will be zipping around on the buses to get all around the resort! Have fun!