Does anyone recommend any particular command line SVN client for Windows. Being 64 bits would be a bonus.
I do have TortoiseSVN, but it doesn't come with command line, which is required for my build scripts. I searched the subversion site and found not one, but four different options. Therefore, my question.
SlikSVN (download) looks like the most appropriate option given what you want.
They aren't 64-bit, but the official Collabnet binaries work fine in 64-bit Windows:
http://www.collab.net/downloads/subversion/
Again its not 64-bit but this is a good open source client http://sourceforge.net/projects/win32svn/
Beware compatibility among versions. if you cmd line commit, you can cause yourself unexpected problems for say, Hudson/Jenkins automated builds if the svn versions are not compatible.
See e.g. Jenkins: invalid version of SVN working copy
Some might think it ironic, that a versioning system has backwards compatibility issues that can bite you :)
Run again the installer for TortoiseSVN. Select "Modify", then you can select to install also the otherwise optional Command Line Tools.