I need advice on handheld GPS units.

I have a Garmin Oregon 450.  Use it while geocaching and also  while riding my bike.  I keep track of elevation, distance traveled, speed, max speed,  moving average speed, stopped time and total time of ride. Great unit and Garmin site will keep it updated. Caching is a great hobby. Some cache's are specifically placed to appeal to children. I am a premium member on the geocaching.com web site and find it to be very user friendly. I am leaving shortly for a ride on the Ghost Town trail and along the way I will be searching for 3 caches along the way. I hope your wife and grandchildren end up enjoying caching as much if not more that I do.