For dads who love nature, think of a new pair of hiking boots or an electronic device that repulses mosquitoes. This device makes a high pitch tone mixology that we can't hear but the biting buggers can. Both gifts are ideal for camping-lovers and golfers also. You can typically find these at a sports or camping store.
Instead of waltzing 3d motion multi directional over to the bar to mix a pick me up I would usually find myself shaking and puking the first thing in the morning. I would then stumble to the kitchen and mix up a drink, and then gag and puke until some of the alcohol would hold. After a couple drinks I was usually well enough to start the day.
Every single guy needs a cocktail set. The Padova Complete Travel Bar Set even has a martini shaker and everything he needs to entertain in style. Single guys like to travel light, so the World's Lightest Carry-on Luggage is perfect for the unattached guy on your list. This suitcase is also great for guys on your list who travel frequently for work.
Games can be a fun addition to your Hawaiian BBQ. The traditional limbo is an easy game to set up if you have enough room.. All you need is a pole or cane and two people to hold it. Having a hula competition can be great drinks rotational fun too.
I was happily married at the time, although problems were surfacing between my wife and I because of my alcohol consumption. I also had two absolutely wonderful children who meant the world to me. Finally, we, too, separated because she couldn't handle my drinking anymore.
Ice machine. There is ice in nearly every cocktail. Piddly ice-cube trays will not hack it when the drink orders come rolling in. Even a small ice machine will expedite the drink making process.