3D software for 3D printing

Hi all,

Does anyone have recommendations for 3D design software that has been used in the Classroom that work with 3D printing weather it be using a Makerbot or other product.  I'm currently experimeniting with Google Sketchup and have used TinkerCad with a Makerbot? However, I wonder if there are other recommended platforms to try out and if so, would love to see some projects made by students.