One thing I will comment is if you choose to put it in the root domain, then , oh submit galleries to the hun on that domain and use the seo re-write mod in wordpress, you can cause some slow-down issues on your server, because your .htaccess for the rewrite being in your root domain, every hit is filtering through that. I had this happen to me, and had to move my blog. It only caused issues though when I had that much traffic.
After I moved one of my blogs off the root, I noticed no traffic, then I noticed yesterday the traffic is picking up, but no referrers. It looks to me like people actually are bookmarking it, which makes me feel good.
Now, my blogs I have left on root domains, I won't submit those to TGPs. FYI