We have Motorola Talkabout 35 mile two way radios that we use occasionally. The 35 mile range would be in open line-of-sight areas (ocean, large lakes, fields, mountaintop to mountaintop). The actual range is much less, however, these are useful around campsites and when you have a large group hike where the front of the group splits off from the back. The Talkabout radios have decent battery life and good range, offer a large number of frequencies, are waterproof, and even come with an emergency flashlight.
Two low tech but lightweight, inexpensive and useful tools are whistles and mirrors. Although GPS and cell phones will get rescuers to your general location, they may be several yards off, which in a heavily forested area could impede rescuers from finding your exact location. A standard whistle will allow you to signal rescuers with little effort. Likewise, a small handheld mirror can be used to signal air-based rescue crews as to your location. Both mirrors and whistles have the added advantage of not requiring battery power to operate.
Two other devices which we don't have are sat phones and PLB's.
Satellite phones tend to be expensive to purchase and require expensive plans to use. The ones that I have used in the past have required an access code followed by the country code and full 10 digit phone number. In a true emergency entering 16+ digits under stress could be a significant challenge.
Personal Locator Beacons (PLB's) are one-time use devices that are use to send distress signals. They typically last 5-7 years on a battery (provided they aren't used). Most have GPS capability as well as 406 Mhz signalling, which sends a unique signal to rescuers when they are close to your location. PLB's don't require monthly plans and just require that you register the device. This site has a nice summary of PLB's: https://www.sarsat.noaa.gov/emerbcns.html.