I think the easiest and cheapest way to make your blog more efficient would be to use a leaner theme with less graphics. The CloudFront seems a bit overkill for blogging. It seems to more appropriate for bandwidth-intensive applications like video, audio, and software downloads. If you have such files that are not hosted on sites like YouTube, meaning that your site's bandwidth is being used, then CloudFront could be very practical. I know that a lot of software download sites, for example, make you host the files on your own server, so if your program is really popular, that could get quite expensive - you'd probably need a dedicated server costing hundreds of dollars per month.