Mrs. 103 and I have two dogs presently, and fencing in our yard is one of the best things we've ever done.
We are both experienced dog owners, and had dogs with our families before we got married. So, we have a little experience with this. The simple fact of the matter is that even if you train your dog to stay on your property, that training will not be rock-solid overnight because training takes time. If you get a puppy, the training will absolutely take time as young dogs can be rebellious and willful just like adolescent children. If you get a rescue dog (all of mine/ours have been rescues from various places), the training will take time as you try to correct bad habits, or teach older dogs who were possibly never properly trained at all. It only takes once for your dog to chase after a horse and buggy for you to wish you could go back in time and put up that fence. Otherwise, the only time your dog will be able to safely leave the house will be on a leash with either you or your husband on the other end of it. We lived in an apartment for a year and a condo for four before we moved to the house we live in now. We put up a fence a few years later and our dogs' lives have been much better. Running free beats being on a leash every time, and you will enjoy playing with your dog more. You can still walk your dog around the area, but also let him run as well. Fenced in yards are also ideal for doggy play dates.
Mrs. 103 once decided to let Lola out into the front yard off leash one morning before work because the back yard was too muddy. She wasn't worried about Lola running off because Lola always does what she's told. But Mrs. 103 didn't expect a red fox to be trotting through the neighborhood, and since this is officially 'Lola Country,' she took off down the street after the fox. Thankfully, the fox eluded Lola and she eventually decided to come when she was called. That doesn't happen in a fenced in yard.
Bear in mind that you will still need to supervise your dog to some degree even if you have a fence. Small animals such as skunks, rabbits, groundhogs, woodchucks, squirrels, etc. WILL find their way in. I tell people that the fence is to keep my dogs in, not necessarily to keep other animals out. If I let my dogs out at night, I have a floodlight that I turn on, and I go out ahead of them to scare off any 'trespassers.' We get rabbits mostly, but if you've never had to de-skunk a dog at 11pm, trust me - you don't want to.
I'm not a fan of electric fences, shock collars, or anything like that. In THIS dog owner's opinion, a good old-fashioned chainlink fence is the way to go. If you want any further evidence that a fence is a good idea, visit any dog trainer out there. I've never once heard of a trainer whose training area didn't have some kind of fence.
Are you an experienced dog owner? What kind of dog are you getting? How old? From a breeder or a rescue?
Regardless of your answers to any of these questions, a fence - in my opinion - will only make your experience and your new family member's better. It will be worth every penny. Trust me.