Robert,
This should get you exactly what you need. You can use this for any document type, simply change the parameter.
CMS.DocumentEngine.TreeProvider provider = new CMS.DocumentEngine.TreeProvider();
DataSet eventDs = provider.SelectNodes(CMS.CMSHelper.CMSContext.CurrentSiteName, "/Your/Alias-Path/%", "", true, "cms.bookingevent", "EventDate >= '" + DateTime.Now.ToString() + "'");