Yep, I like TWM on design too, but both CTWM and IceWM can be equally configured.
On CTWM, you can straightly import the TWM config modulo some slight error on a single
line (if any). Once you set profer TTF fonts for it (by default they might look huge on smaller
screens), you are done. Set the sticky/persistent menus (on a laptop/netbook it's a godsend)
and you are done.
Maybe you would like to disable the startup screen (-W flag for the 'ctwm' binary) or some obvious option in the man page in order to be put at ~/.ctwmrc or ~/.twmrc.
For sticky menues you need to just put
StayUpMenus
at ~/.ctwmrc
Just copy the content from your former ~/.twmrc file and append that
on top.
Also, if any, CTWM (with the welcome screen disabled) can be as good as TWM but with better features (sticky menus and the like).