How you record the changes is pretty key to how you report them, but not necessarily critical.

If you want to regularly query the data, then you either need "active auditing" (usually done via triggers), or Change Data Capture (Enterprise-edition only, unless I'm mistaken). Either of those will generate a set of queriable tables that you can base reports off of.

Depending on how flexible you need the reports, either pre-built reports in SSRS, or something really flexible like Excel pivot tables (or the Sharepoint version of these), would be worth looking into.

If the primary goal is to see the history of a room, that would easily be done via SSRS. A drill-down report, where you pick a hotel, then a room, then details of changes, would probably get what's needed. History of a guest would be done via some sort of CRM-type application. Aggregations like "how many reservations were cancelled per room, per hotel, per month" would probably best be done via pivot tables.