Our 8yo German Shepherd can't stand being left alone, we know, and as soon as he hears the clink of keys he's running to the door to make sure he isn't left behind. DH and I both work from home, and DCs are getting old enough to be left home for short periods, so there really is just about every minute of the day SOMEONE around to keep him company. I can't say we've NEVER left him for more than 4 hours, but (a) it's pretty rare; (b) it's never been much longer than that; and (c) it's only happened when completely unavoidable. We always make sure he has a long walk before we go out.
We try to take him with us in the car whenever we go out, and the only reasons we would leave him behind are: the outing being completely unsuitable for any dog; the close proximity of other dogs (like going to DH's sister's, where she has two - pubs are not the same); or the outside temperature making it unsafe for him to be left in the car. If at all possible he would far prefer to be left in the car for a little while than by himself in the house - I think he feels more confident we will return to the car than to the house, for some reason.
Getting a dogsitter/dogwalker wouldn't really work for us, because he isn't great with strangers entering the property and he isn't great with other dogs. Once we did go away to the US for Christmas, and we got a house sitter who looked after him, which worked out fine, but he had gotten to know her before we left and was used to her. He had had a bad experience in a kennel, which my DH had to put him in at the last minute when his mother became ill and couldn't look after him when we had to go away, and DH vowed he would never again go into a kennel.
A dog really is a tie - it really isn't something that can be undertaken without very careful consideration being given to how he/she is going to be looked after when you aren't there.