I have the Golf Buddy Voice and absolutely love it. Super small, clips onto your belt or hat and can speak up pretty loudly if you want it to. Also Sub-$100.
http://www.amazon.com/Golf-Buddy-GolfBuddy-Voice-GPS/dp/B00S2SC9V0
I have this and I love it.
Unless your dad is a very atypical 70 year old, this is exactly what he needs. No fiddling required and all the info you really need.
I use this http://www.amazon.com/Golf-Buddy-GolfBuddy-Voice-GPS/dp/B00S2SC9V0 which is a GPS but also allows you to set a start and end point while you're out on the course, to see how far your shot was