I thought with someone else's blog post, you just had to make proper attribution to the original author and site. Didn't think you had to get permission. Do you?
Actually, you do, in most cases. The only time you don't need to ask permission is when the author of the post has granted you a license to copy it, which is what a CC license would be. And even then it can be conditional, such as when the author specifies non-commercial use only.
If I was careful, there's a massive copyright issue there.
Show me one place where there is not a copyright issue nowadays. It's long past ridiculous.
No copyright issues with this sort of sharing, since the author of the site has to agree and sign up at repost, first. That is giving permission for the article to be shared in full (ads and all) on someone else's site. Since the author preapproved the sharing, there is no copyright violations involved.
So my content will appear elsewhere but 'nicer'?
Yes, but not just nicer formatting. You get the page views, your ads displayed, proper attribution, and since it's done in an iframe, it won't look like duplicate content to search engines.