OK, so I went to Garmin's website and pulled up the user manuals for several different models and found that they pretty much all do indeed have this functionality. I wonder why none of the salesclerks in any of the retail establishments that I have visited and asked about this knew that? Oh wait, I do know why. Salespeople in the big box electronics stores don't know jack diddly squat about what they're selling. Oh, well. Guess I should have been using Garmin products all along. Thanks, guys, for steering me in that direction.
Fly fishing - it's cheaper than a bass boat!