What you need to do here is adjust custom normals on the planes than needs to be flat. In maya it's much more easier than in max. Is max you need to use Edit Normals modifier or go for custom scripts http://www.scriptspot.com/3ds-max/scripts/improved-face-weighted-normals…
Can we please stop posting scripts that automate the proccess. AFAIK this thread is about topology and how to handle subdivision effeciently. If people keep posting script solutions, noone really benefits because one doesnt know (especially newbies) how topology affects the surface etc. These tools are awesome and time…