I would recommend the Garmin 76Cx or the 76CSx, then the 60Cx or 60CSx, and third the Garmin Legend HCx. Of the three models the 76Cx(csx) have the largest screen.
I purchased a 12V power cable for my 76c & 76Cx from this source.
http://www.gpsgeek.com/products/12v-dc-power-adapter-for-garmin-4-pin-streetpilot-iii-gps-v-gps-iii-60c-60-60cs-72-76-76c-76cshttp://www.gilsson.com/gps_cables.htmThe 76Cx & CSx have the largest screen. The down side with senior eyes is that for driving the screen is on the small size. It is a compromise to because a good automotive unit is too big to carry around in the woods for most of us. The gps can be a distraction while driving.
The user has a number of options. When driving I select a different set of screens(pages) then I use when hunting. Normally when I am driving I have the tones turned on, when hunting I have the tones turn-off.
Yesterday I had to go to a medical center in a large city. I generated a waypoint for the center and when the wife and I left the house I brought up the waypoint and selected the go by road option. It worked great.
You can set the unit to see as many pages as you want. I like to manage them so they are related to my current activity. Example when navigating down the highway I have the Turn Preview page setup after the map page. When I am hiking the woods I the Turn Preview page unselected.
During the hunting season I have the Sun and Moon page in the line-up but after hunting season it is out of the line-up.
I have packed the Legend, the 76C, and 76Cx around for a few hunting seasons. I love the size of the Legend, but the screen size is a limitation for some. Because I spend some time on the water I like the 76 series because they are a floater, not a sinker.
So when I am out hiking the Legend is the right size, but the bottom-line is the 76 series would be my go-to unit most of the time.
Normally when I leave the house for a hunt I have my gps on 12v power. Out of the vehicle and hunting I be on AA batteries. Alkaline batteries last longer then rechargeable batteries. But I use rechargeable batteries for everything except extended hunting. I have found that alkaline batteries will last two or three days in the woods. Lithium Ion AA batteries can be used, but Garmin cautions that they should be discharge some with a flashlight first because they run at a higher voltage then the unit is designed for.
Caution: If your wife has been navigating for you, and proud of her navigation skills you might want the gps unit operating but set aside. The gps unit can be used if needed as backup.