K.
I had the same problem as my older child is a girl (6) and her potties did not work for my son. I got the Bjorn potty and it is wonderful. He can sit on it easily without having to stradle the protector thing. He really likes it too. It's no frills, but works great.
And, if you want any advice, I'm a proponent of the sit down method for boys. Standing up for a 2 1/2 year old just gives him to much "creativity." Good luck