GPS with maps for touring / using an iPhone
If you have an iPhone or an Android phone there are various free options, some based on OpenStreetMaps, but even Google's own solution is excellent. For google maps you can download areas to store locally (for those areas you know you will have no connectivity) and it is free!

I'm playing a lot of Ingress at the moment, which requires 10 - 20 hour stints with my phone continuously running GPS, with the screen on (ie very high load) and my solution to the power problem was this 12,000 mAh battery pack from Amazon. It is only a little larger than my Galaxy S3 so sometimes I hold it with the phone, or I pop it in my rucksack.