Should I build a Blog Network?

Yes build a network and rank your sites.

Those are really good domains.... if any of them are left alone, do let me know. I will grab them. PM me.

Build out the domains with better metrics first. If these are sites you've owned for some time make sure you vary the whois info. Otherwise, if google identifies one of your sites as a pbn and they all have the same whois info they will all get taken out. Since you just have the domains laying around you may not have thought much about whois or where they are hosted so make sure they do not have a footprint.