First consider who your audience is. If you would like to reach the general touring community I think Crazy Guy On a Bike is a slam dunk. I know that when I did my first coast to coast (Trans America) we met a lot of folks who were doing the route at the same time we were. It was kind of cool to meet folks in person on the road that we had originally met on cgoab while planning the tour.
If family and friends are the only audience then I'd be more inclined to go with Facebook, especially if short quick updates are what you want. Using a FB phone app makes it quick and easy.
If you are more interested in doing more writing and are not after the cycling community then Blogger or Wordpress might be the way to go.
On the other hand if you mostly just want to let friends know you are ok and maybe send a picture now and then using group text messages may be the way to go. Service providers do often have a limit of 10 or 20 addresses for a group text, but I think there are work arounds.