Konda,
I think you are right on track. I always recommend to people traveling with kids, even tweens, that they consider going back to their resort daily for some rest and relaxation. After all, isn't that what vacation is all about?
So as you probably know, you have to take into account the time you will wait at the resort, or the park, for your bus. That can be up to 20 minutes, but I rarely have ever had it take longer. Often I will find my bus arriving within 10. That considered, bus times from Port Orleans to the resorts typically are as follows;
- Magic Kingdom: 15 to 20 minutes
- Epcot: 10 to 15 minutes
- Hollywood Studios: 15 minutes
- Animal Kingdom: 25 minutes
With the Animal Kingdom, it is not a park you may choose to return to in the evening, due to early closing times (5 pm most nights). So with that park, stay through the early afternoon and see all you came to see. Then return to your resort for a late afternoon break, and go somewhere else for the evening (like maybe Downtown Disney).
For the other parks, consider it a 35 to 45 minute trip each way, including waiting for your bus, and time getting around the resort.
BOTTOM LINE: The younger your kids, the more essential this move is. I say
DO go back to your resort for afternoon breaks, with the exception of the Animal Kingdom.
Have a magical vacation!