How about theming it around a particular cuisine (Italian, Mexican, etc.) - one that your DH particularly likes? Gives you a chance to do something a bit different with the food and the drinks! You could do themed cocktails, beers and wines as well.
Decorations can go a long way to creating a special atmosphere. They don't have to be cheesy or match the food theme if you go with that. Will the party be in your backyard? You could set up a gazebo and hang curtains or fabric from the top poles, and maybe have the food table and cake under it. Sort of like this: http://www.furnishingtouches.ie/images/cur.../outdoors_1.jpg
- although the curtains there are pretty feminine, you could choose some more to your DH's taste!
Lighting is important too. Again, fairy lights or paper lanterns might be a bit girly, but you could make some brown paper bag luminaries (with battery candles so there's no risk of fire), or hire some coloured spot cans to illuminate parts of your outdoor space in a cool way. There's always the good old tiki torch too.