If you are flying a smaller GA aircraft, you can approximate the L/D Max airspeed by using something near Best Glide speed or about 1.3 Vso. Since the L/D curve is broader near the peak, you won't lose much endurance if you are a few knots off.
As for larger aircraft that have an AOA indicator, best endurance is already figured and published as Vhold, which varies with weight. The wings of faster aircraft aren't as efficient at slow speeds (when they're clean) as GA aircraft, so the L/D Max speed is a little faster.
The CRJ doesn't even have an AOA indicator in the cockpit. I know it measures it, for windshear detection and such, but they give us no representation of it, unless I'm missing it somewhere. I guess they didn't think it was that useful.
I was always under the impression that one application is coming in for landing. If you are at ref and landing config the needle should be in the 'sweet spot'. Always seemed to work. If it wasn't I guess it meant you weren't doing something right! Let us know if you find any other uses.
The ERJ doesn't have a digital readout of Alpha, but it has a realtime "low speed awareness bar" which appears on the speed tape, and marks how close to stall you are. It moves up if you add any g-loading at low speeds, and it will show what's happening to the Alpha during a turbulant approach. It can be very useful in validating your approach speed, too. Typically, your Vref bug is right near the top of the green portion of the bar. If the bug is toward the middle or bottom of the green as you are fully configured on final approach, that means you are heavier than you think you are!