I found these great, simple ideas to celebrate a homecoming. They are from Navy Wives Online. These would be great for any homecoming, not just military.
Make a banner to hang over your fence, patio, front door or garage. You can get a plain bedsheet for about $5, and use craft paints to make a great welcome home sign!
Paper chains decorated by the kids make great decorations to hang all over!
Crepe Paper streamers and balloons
Sidewalk chalk to make signs on the drive, walk, and patio, welcoming home your sailor
T-shirts with photos of the family, or special pictures, anything special to say welcome home
Favorite Flowers, vased at home or wrapped at the homecoming
Decorated dixie cups (you can get these hats at Oriental Trading.com)
Plant some special plants, flowers aroudn the house to dress it up for a spring or summer homecoming
Holiday lights are a great addition to make the house pop out if you are driving up in the evening, If you are not going to be home for a while, you can get a timer to set them on, and have them turn on just before you get home
Take your special sailor out to a nice dinner
Plan a night in with family, playing board games or card games
Run a hot bath or shower, light a few cadles, and invite your sailor to wash off that boat residue, and relax for a few, and then enjoy a body massage at yor own skilled hands
Make a special dinner with their favorite foods
Invite a couple friends over and have a laid back movie night, or get together to catch up, and just take it easy
Take your sailor out for a nice walk to see the neighborhood, or even just the mall
A special card made by you and/or the kids
Dinner out at their favorite restaurant
Video games that have been released since your sailor went on deployment/underway