make more rare content type appear in result
AFAIK you'll have to manually modify the query to get such advanced conditional sorting. 

You could group by the type (under Format), and set the Pager to such a high number that you can always be sure there will be at least one Resource there, so the second group will appear for it. But it's not a very reliable method if you can't predict the longest range of blog entries without Resources. 

Usually, this is handled by creating two Views displays, one for blog entries, and the other for resources. You can set the Resources one to be Attachment type, and attach it to the blog one so they display one below the other. In that case you will be able to override the number of items in the Pager to show less Resources than Blog entries, to show Blog entries are more frequent.