Very good points. I always give my wife the plan and get in touch to tell her when I am off the mountain. Often this is not easy so she knows that it may be a while after I am safe before she gets the word. Cell phones are of some use, if you have coverage. I am on my second carrier and neither has worked in most of the places I ski: Canaan Valley, Mad River Valley (VT), Alta, also places I hike like Shenandoah. Where there are few or no customers to pay for coverage, coverage is scant or non existent. Sprint didn't even work at Burke Lake Park in Fairfax County. Before cell phones I used roadside phone booths and a toll free 800 # we set up so the kids could call toll free. I also have a personal locator beacon; http://www.findmespot.com/en/
It is not as easy to use as advertised and I've never activated the emergency button that calls in a rescue. I hope it would work. In the event of a massive heart attack, in backcountry or walking alone on a city street, you are probably out of luck. I've had a 'silent' heart attack and a triple bypass and so I get checked regularly and have thought a lot about it.
No doubt you detect my skepticism about electronic devices. I think that brains are the most important thing to carry into backcountry; you can always get coverage.
Some places where I have gone solo:
Whitegrass and surroundings. Very often. Few people my age will do this so I am always a drag on the younger folks on the climb. Rather than exhaust myself trying to keep their pace I just go alone. Almost always there are one or more people when I get to the goal and I know the lay of the land well so this is not really very threatening. I feel safer there than in the crowds of yahoos at Timberline and CV. I give Chip, or whoever is in the lodge, the plan.
Mt. Washington, NH A mountain that is justly famous for its severe weather and the rapidity of weather changes. The plan is on file and I keep a watchful eye. In winter I stay low and out of run out zones. In spring I've been caught in a thunderstorm near the top of Gulf of Slides, and in fog that closed in over 15 minutes near the summit just 2 weeks ago. A recommended read is "Not Without Peril" by Nicholas Howe.
St. Mary's Glacier, CO Easy access and easy out, usually people there.
Loveland Pass, CO Park near bottom, hitch rides to top, hike out ridge ski down. Also easy and usually people there.
Indian Peaks Wilderness, CO (Isabelle Glacier and Rollins Pass) Much more committing, people near trailheads probably not once you get to the skiing.
Tioga Pass, CA Took a 'water taxi' across Saddlebag Lake with a bunch of fishermen, arranged my return time and hiked up Mt. Conness alone. Turned around below the summit by a thunderstorm.
Yosemite National Park. Took the lift at Badger Pass ski area, signed out at patrol shack and skinned & skied untracked powder on the backside all day within 1/2 mile of people but in complete solitude. Signed out and skied down the groomed slopes to my car.
Sequoia National Park My Mammoth buddy was out of town so I took a well known backcountry trail skied untracked snow, saw just a few other people in 5 hrs.
Rabbit Ears Pass, CO near Steamboat (not alone) Took my 11 yr. old grandson on his first backcountry ski. He loved it and wants to do more.
Nebraska Notch, Stowe backcountry, VT Last year, a -30 deg. day. Got scared when about 1.5 miles in and came out short of the goal. I felt warm when skinning but stopping for a rest the cold began to chill me to the core within 60 seconds. There is an expression among ski mountaineers, "The mountain will always be there." I knew the nearest human being was at least 5 miles away and decided to come back under better conditions.