Best Blog Site and Map Software

I can recommend against wordpress.com. They don't allow iframes, which makes it impossible to directly embed (most? all?) online maps.

I’ve used and recommend Tumblr. Easy to post, allows iframes, very customizable, and free.

I use Hillmap for online route planning. It can generate an iframe view of your map that you then embed. Just edit the “height” and “width” to suit.

Tumblr's weaknesses are that it isn't really designed to handle comments/discussions, although some themes allow you to add Disqus, and that it's a stronger medium for visuals but weaker for text. OP, if you plan visual-heavy trip reports, tumblr would probably be a good choice. If you plan on doing a lot of writing, you'll probably find the interface frustrating quickly.

postholer.com is designed as a trail journaling site. Trailjournals.com works well too; I prefer postholer, in part because I can journal from the trail or trail towns (it works well with mobile devices). Postholer also does the whole mapping thing you're looking for (I don't believe that TJ does). You can punch in coordinates yourself or if you carry something like a SPOT you can get a nice plot of where you were along the way. I normally don't do the SPOT thing, but I did on the CDT, did a check-in twice a day every day.

You can see how that looks on my journal, at http://www.postholer.com/brianle
On the CDT journal (likely the currently active one, for now at least) click "Continental Divide Trail Map" at the bottom of the sidebar. Zoom in. Hover your mouse over any of the yellow 'S' circles and it tells you the date and time that I checked in there and gives GPS coordinates.

The site owner has added quite a number of features over the years; here's a good summary: http://postholer.com/journal/index.php?trail_id=1