How about creating content that readers actually want, and allowing them the options to share it? You can chase back-links all you like to get a better ranking, but if the content is not doing anything beneficial for the visitors it's all a wasted effort. Why seek a high position when the content is not likely to keep you there? You'll get there for linking, but then the bounce rate and the lack of interest shown by visitors will soon have you back to square one.
Always focus on getting high quality backlinks because I have experiences with low quality and high quality links. 1) I had some sites that I just promoted with links from low quality web directories, and despite having hundreds of backlinks some of these sites never got a PR1. 2) I had few websites having only 10 backlinks and got a PR3 on last PR update. That’s because one of those links was coming from relevant and quality sites.
If those 100 PR2 blogs are good quality, relevant to your blogs and you added your links in a natural way within a guest post, it will help to increase your PR and Authority. You will also get more chances to get good ranking in search engines.