The list view may work well if users have very specific and inflexible dates, times, and durations. Then you may want to provide a Search/Query dialog for those parameters and list the results in a list view. This makes it easy for users to see an exhaustive list of the possibilities even if they span wide ranges of dates. It works best if all results that fit the entered criteria are pretty much equally satisfactory regarding date/time. Users can then explore and select an option based primarily on non-critical non-time criteria (e.g., Does the room include a projector? Which one is nearest my office?).
Graphic depictions such as calendar views, are probably best if your users have flexible or vague criteria (e.g., an hour or two sometime the week of the 21st, preferably in the morning) or are interested in the relations among the “rooms” (e.g., to accommodate an all-day meeting on the 3rd, use Room 201 in the morning and 314 in the afternoon). These allow users to explore the options on time-based criteria. Among the graphic options:
If the times and/or durations are inflexible, but the dates are flexible, a calendar view may be okay, where you show days of the week on the X-axis and weeks of the month on the Y-axis. The identity of the options are listed in each day’s cell. The user can then choose best date. It works best if other non-time criteria are not particularly important or can be inferred by the option identity (e.g., users know that Room 201 is the “big conference room”), so users don’t have to drilldown too much for details.
An appointment book view, with date on the X-axis and time of each day on the Y-axis may only work if there are few options (five or less alternative “rooms”). Available times within each day can then be highlighted (or non-available times blocked off). Then the “appointment books” for each option may be shown side by side or the user can “page” among the options.
If there many options, then consider a Gantt chart, showing available times as stacked horizontal bars over the X-axis of date and time. For a 1000-pixel-high window, more than 30 labeled options may be visible at once. Users can zoom in on a particular day or week to see in detail what is available at what time for how long. Non-time criteria for each options may be shown in fields in an adjacent pane, like a list view
Perhaps for an intermediate number of options, you could try a hybrid Gantt/appointment, with each day having Gantt bars for each option. You could try an appointment book layout, which may be familiar to your user, but I think a substantial numbers of options would fit better with time on the X-axis and date on the Y-axis.
Any of these graphic options can be combined with a Query/Filter feature as required for your users to help narrow their searches. This can prevent too many irrelevant options from cluttering the graphics.