I can describe them easily.
I saw one clear a 5 foot fence without taking a running start.
That's high energy.
On another note, I leave my dog alone for periods of 4-5 hours at a time during the morning. I see her for an hour at lunch and then back to work for 4-5 hours. And even in the short span of a few hours, she's managed to do some pretty good work on some of our things.
Dogs don't like to be left alone. Ever. They can't understand why they got left behind.
If you want a medium sized dog that wil fit into a 3 bed apt, consider a bulldog. They are like rugs.
But from your description of your lifestyle, I don't think a dog is for you right now
. It wouldn't be fair to the dog and you'd miss out on all the best parts of having a dog.
Remember that you always have to consider what you'll do with the dog if you go away. Overnight trips can be a hassle because you either have to find someone to watch the dog or take it with you.
Dogs are more difficult to have than kids cuz you can't take your dog everywhere you go.