Hi C. - I think you will shortchange your eldest by not sending him/her to an academic kindergarten, especially since he/she will be six next school year. When LB says they don't cover kinder academia it means that they focus on social skills rather than academic skills. My son started 1/2 day kindergarten in Parker as a just turned 5 yr old and I was amazed at all that he learned. He went from being a pre-reader to a full-reader by the end of the year. His writing skills went from almost nothing to writing sentences. They did little things like telling time and reading calendars and they learned to write out their names and phone numbers. They also learned a lot of math skills like counting to 120 with 1's 2's and 10s and they were taught pre-algebraic skills.
My son rode the school bus to school and I picked him up at 11:30. It was challenging but over in a flash and now he is at school all day and rides the bus to and from school. Many of the Douglas county schools have in-school after care programs and KinderCare was also there with a bus everyday to shuttle kids to their after school program. So you could put your twins in pre-school and your son could go to the aftercare program (more social and arts oriented)
I hate to tell you this, but the term "soccer-mom" is a mis-nomer. We're shuttle moms. If you are concerned about time in the car, maybe you could coordinate with other kinder and pre-school moms and form a car pool?
As far as charter or private schools, I encourage you to take the tours they offer and also interview the principal of your community public school. We had all options open to us and we liked the public school the best. It has proven to be the right choice.
btw - I am SO jealous that you have your 3yr olds in full-day preschool! I take my 2.5 yr old son to the babysitter 2 mornings a week but it's while I work a PT job.