I've always experimented with different X11 window managers and desktops. There was a time when there was actually significant choice and variety, and a lot of energy to go with it.
I simply never got on with either SunView or OpenWindows, much preferring awm or tvtwm. And while CDE had some useful utilities, the desktop itself drove me to distraction. I appreciate the strengths of KDE, but can't get on with it either. I currently use either the Solaris JDS build of GNOME or a home-built version of XFCE as my primary desktop.
I spend a lot of my time living inside VNC sessions, and there I run Window Maker. I've always liked Window Maker - fast, lightweight, and there were oodles of themes available. (A theme here is a desktop background and a colour scheme for menus and window decorations.) Unfortunately availability of themes is now limited.
I've made available my own Window Maker Packages for Solaris. These include the software and integration with either dtlogin or gdm, and will work on either Solaris 10 or OpenSolaris/OpenIndiana.
Included in those packages are a couple of simple themes I've put together based on OpenSolaris and OpenIndiana, which you can also get directly from the above link if you already have Window Maker running.
I also run, at times, many of the other older styles of window managers, from the basic twm derivatives up to enlightenment and AfterStep. Hopefully I'll be able to find some time to get those properly packaged up as well.