I am using Visual Studio 2012 Ultimate RC, and I did install the Sharepoint 2013 tools. But cant find the site definition templates. Any thoughts??
With the SharePoint 2013 tools they removed the Site Definition project template, but added Site Definition as a project item.
So you have to create an empty SharePoint 2013 Project and the add a new item of type Site Definition
I am not sure what steps you followed, please look at this MSDN instruction and check if you are doing it right.