I have had the best results with using the Event aplication's (most have it) intergration to Salesforce and then pulling the appropriate data down into Marketo via the intergration with Salesforcemay require some field mapping between objects in Salesforce based on event partner)...Once the reg data is in Salesforce you can see it down in Marketo an trigger smart campaigns of the "change-data value" in the fields you are watching and then use Marketo smart campaigns, emails and landing pages for the appropriate assets and wsorkflow associated with the event...