As mentioned above, if you will be within cell phone coverage and you both have iphone's, you can use the Find My iPhone/Friends apps for minimal cost. If you want tracking outside of cell coverage, then look into the Satellite services, but they come with usage fees. I use a Delorme Inreach (primarily for solo motorcycling/backpacking) which is more expensive than SPOT, but has global 2-way text message communications. Both have tracking and PLB (call for S&R) functionality, but I require 2-way comms that are not of an SOS EMERGENCY nature - like "Honey, I bent a wheel, send a cab to xxxx."