Unlike GNOME 3.x or Unity, both KDE and Trinity are designed with the assumption that panels are places to put frequently used small tools and notifications of various sorts. Taskbars, notification trays -- all the classic features users have learned to expect in a panel -- appear in both desktops.
So, too, do most of the configuration options, although the fact that KDE's are visually oriented and minimalist may disguise the fact. In both desktops, you can set the size and location of the panel, and whether it hides to give more space for displaying open windows. The main differences are that, to change the background of a KDE panel, you have to adjust the theme rather than changing it separately, and that Trinity has a number of pre-configured panels that you can choose that require considerable customization to reproduce in KDE.
Verdict: Trinity. Despite improvements early in the KDE 4 series, the KDE panel is still not as convenient to configure as Trinity's.
The menus in KDE and Trinity are mirror images of one another. For a default, Trinity offers a classic menu, with sub-menus that spread across the desktop, with the option of switching to a Kickoff style menu contained in a set-size window. KDE offers the reverse: the Kickoff menu with the option of switch to a classic style menu. Both Kickoff and the classic menu can be manually edited, although you might miss the KDE menu editor, which is hidden behind a right click on the menu button.
Verdict: KDE, but just barely.
Virtual Desktops and Activities
Little changed in the options for virtual desktops between KDE 3 and 4. However, current versions of KDE also introduce Activities -- independently configurable desktops that you can switch between depending on what you are doing or where you are, each of which has its own set of workspaces.
Because of Activities, you can have more customized work flows, such as starting KDE with an overview full of widgets, then switching to a more conventional desktop as you settle down to work. They are more complex than anything offered by Trinity, but convenient and efficient once you are used to them.