Can I ask something, the modular assets stay within 3dsmax and you model whatever you want or do you put them in the engine and build everything there? And do you make holes in the wall for windows or do they float over the walls?
I used to have the same feeling when I did architectural visualizations with 3dsmax. Since we couldn't change the dimensions of the models, we removed walls and placed the camera outside the rooms... like shooting a room through an open window or door.
Can't answer the sketchbook question, though for "how to and is it possible to make from high poly to low poly" you might want to search for 3dsMax Retopology: http://www.google.ca/search?sourceid=chrome&ie=UTF-8&q=3ds+max+retopology
I can't do much than this, since we experience the very same issues that your facing with 3dsMax. We are in the same boat. 3dsMax2012-2014 are experiments. Maybe try "msconfig" in the Run command-prompt and remove any unnecessary underlying programs.
3DSMax is all about the gpu as far as viewport performance is concerned. ZBrush uses software rendering so its CPU bound. A fast HDD is also important for ZBrush sense it uses virtual memory (its own, not what windows provides) extensively.
Thanks guys. @DottyPixel - I'm just using 3dsmax. For a lot of the complex shapes I fuse primitives with boolean intersection/boolean cut, and then just pull verts around and the usual :) Other then that I use plane modeling (like the fin/wing thing).
I recorded a video tutorial for bodypaint in conjunction with Photoshop and 3dsmax as part of my Delilah series. I'm almost there in terms of editing, documenting and uploading. I've made it to the UV stage, and next will be texturing. Not sure how soon, but hopefully in the next month or so.
I want dibs for the non-high profile company guys :p . I'd love to experiment with this on various level editors i'm working with at the moment, torque, unreal, unity etc... and of course make mad useful 3dsmax setups for weird modelling workflows :) !!
If you want the real deal do most of it in 3dsmax. Make a few bricks and clone them. If you want to take it into mudbox make sure to set up the bricks so they sub divide well. http://www.doom3world.org/phpbb2/viewtopic.php?t=17688
Autodesk Maya (can sign up for a free learning edition), Autodesk 3dsmax, Softimage XSI, Lightwave, theres acouple of more free and cheap programs I'm sure someone else knows about but can't recall off the top of my head.