Go for the 120*F. That is what is recommended by public health officials for homes with small children (and about the lowest you really want to go with bacteria...)

Here's one where different public health recommendations for different purposes are inconsistent.

The 120 deg recommendation is to avoid burns to small children. But from what I've read, that's too low to kill bacteria.

I'd hate to think of what's growing in a tank that's stagnant because of infrequent use. How often are you there, how much time passes in between visits?

If it were mine and hadn't been used in awhile, I'd probably flush out the tank by running the hot tap (which is cold) following arrival, then turn it up to a good med high setting to cook whatever is inside, and then turn it down after a few hours so that it remains at a safer temperature.

I agree that 120 is to low. I have a friend who ended up with Legionella from the bacteria in the low temp vacation home tank. You can turn it down when gone, but as soon as you get there bump it up to 140 and flush that hot water thru the system. Then turn it down to 120. It's a hassle, but....!

Turn it off and drain it before you leave. Even 140 isn't hot enough to kill a lot of bacteria. Then turn on the valve and flip the breaker when you arrive.

Ditto. Turn off and drain. Upon return, fill and turn on.

Draining and letting an electric heater dry could result in the heating element gaskets drying out with resulting leaks when refilled. Not guaranteed to be a result, but possible.

Replacing a cheap 30 gallon due to wear and tear every 5-6 years is still cheaper than hospitalization from a bacterial infection.

Tankless would solve all of the problems, except enough electricity to run it. A gas tankless would be ideal though.

Although I'm confused by the statment that it's turned off when you're gone, and then asking about the minimum temperature to keep it at. Which is it? It's turned off and drained or it's kept at a minimum temp when you're gone?

Another alternative is to run the hot water heater at 140 degrees and add a "hot water extender" valve above the hot water heater to blend with cold water to supply the house with 120 degree water. This keeps the hot water heater tank very hot without the distributed water being hot.

You need 180 degrees to sanitize, 140 isn't going to cut it.