Pods8 and anyone else considering adopting,
There are a number of things to consider. Your comment about both of you working is very important. My wife and I are a childless couple with professional jobs. It isn't uncommon to have long days like you describe. One solution we found was to hire some neighborhood kids that are home schooled to come over each day at lunch time and let the dog out, play with her, etc.
We also had a well established cat when the dog arrived. Don't worry, the cat will let the dog know who was here first. If our dog was walking down the hallway and the cat was in the way, the dog turned around and waited until the cat moved on.
Because our dog was adopted with issues from the start, we were not comfortable with boarding her. If we wanted to go on a vacation without the dog, this made it more difficult. Some of our sources for house/dog sitters included nieces and interns at work. Ideally we looked for college age people that wanted a break from Mom and Dad but were too busy to party.
As to what age of a dog to get, that is a tough one. Nobody wants to bring home a dog that is within a few years of its life span. That is why rescue centers have a hard time adopting out older dogs. But there is a lot to be said for bringing home a dog that has mellowed out and won't tear up your yard and furniture. Ultimately, it will be your call, but keep in mind an older dog has advantages also. Maybe fostering for a rescue place would work, giving you short term dog time.
Finally, there is lifestyle. My wife and I enjoy boondocking. But we are equally as comfortable in the kind of resort that recently drove Kcowyo nuts. We have done some overseas travel. During the time we had with our dog, though, that was limited. We will adopt again, but not for a couple of years so that we can travel again. Granted, adopting a dog isn't like having a child, but you are still taking on the responsibility of a life. You will need to make lifestyle choices.
I am glad to see you thinking about the pros and cons. The reason there are so many animals in shelters and rescue places is because people don't consider the things you are thinking about. Whether or not you get a dog, good on you for thinking it through.