Put the kids on one side (youngest on the window seat,) and you sit on the aisle seat across the aisle from them. You may get grief about having a carseat in an aisle seat, but you should be able to make the argument that it's not impeding the ability of your youngest child to reach the aisle.
Optionally, you could have your older child in a CARES harness, or nothing on the plane - that should make for less grief for having two children in one row.
If the flight's not full and you have the option, I would put both children in the windows and you can sit in either aisle seat, depending on who needs the attention at the time.
That's just my :twocents: though.
It could be worse... the only planes that fly to my parents' airport have only ONE seat on each side (but at least that makes them ALL window seats.
)