Our family considers the Disney monorail as an attraction and not just a mode of
transportation!
There are times of the day in which your girls will enjoy the monorail much more than during the morning rush.
First, you'll want to go directly to the Magic Kingdom to begin your touring as this is the time of day that rides are least crowded. In addition, the monorail is extra busy in the morning and again when the Magic Kingdom closes at night. During these busier times, it is very likely that there will be standing room only once you board the monorail.
For a more magical journey, I would suggest leaving the Magic Kingdom for a mid-day break. Board the monorail at the Magic Kingdom and travel around the resort loop. Look for the Resort Monorail sign. Feel free to exit at the Contemporary, Polynesian or Grand Floridian for lunch at either a table service or quick service restaurant.
To travel to Epcot from the Magic Kingdom, you will need to exit the monorail at the Transportation and Ticket Center and transfer to the Epcot monorail. If you have a park hopper, you might want to plan on touring Epcot that afternoon.
If you simply want to ride the monorail, board the resort monorail at the Magic Kingdom. The monorail will stop at the Contemporary, Transportation and Ticket Center, Polynesian and Grand Floridian before returning to the Magic Kingdom. Once back at the Magic Kingdom, resume touring the park or transfer to a bus back to the Caribbean Beach Resort.
Just for your information, if you board the monorail station marked Express Monorail, you'll be traveling only between the Magic Kingdom and Transportation and Ticket Center (TTC). The TTC serves as the Magic Kingdom's parking lot as well as the transfer hub to Epcot via the monorail.