Having a television, an old sofa, and a few chairs in your garage is fine, but why stop there? If you are going to have a "man cave" to watch football all season, you might as well go all out and really make the most of this valuable real estate. If you have a family, everyone can take turns using this space. Mom's book club or friends who stop by for tea might like a private space to retreat to, and when your kids have friends over, this would be the perfect place to let them hang out. Of course, it is still your man cave, you are just sharing. Even if you don't share, the essentials on this list will ensure everyone will want to hang out at your house during the big game.
Multiple TVs - Rather than flipping channels so everyone can keep up on all the games playing, mount a few flat screens on your wall. You can have one large one for the main game, and then a few smaller ones scattered around. You can pick up smaller ones really cheap around the holidays.
Refrigerator - There is no need to walk all the way into the kitchen to grab a beer. Besides, there is never enough room in the kitchen fridge to hold all the beer everyone brings. A refrigerator in the garage is essential.
Furniture - Old sofas and chairs are fine to use, but you can pick up furniture covers fairly cheap. Suddenly that old furniture looks new again. If you need to buy extra seating, consider bean bag chairs and hammock swings. Most importantly, you need a few small tables. Everyone needs a place to put their drinks, snacks, and cellphones.
Smoke Free Fireplaces - Unless you are one of the few people who have the pleasure of having a heated garage, it is probably pretty cold out there in the winter. A couple smoke free fireplaces will keep the garage nice and toasty. When the power goes out during a storm, hook your television and cable box to your generator, light your smoke free fireplaces, and invite everyone over to watch the game.
Shelves and Organization - This space may be serving as your game day getaway, but it is still essentially a garage. This means you likely still have garage-like things in there, such as tools, sporting equipment, etc. Some industrial shelving and storage bins will get everything organized and hidden, so the space feels more like an extension of your home rather than a garage.