We hosted Thanksgiving at our house this year. About 30 people.  Last time I made a turkey, I bought a brine mix. This year, I decided to make my own brine. It turned out really well. I would probably add more spices and salt next time. I started with this recipe found at allrecipes.com, but adapted it as suggested by reviews to the following:

Turkey Brine

20-25 lb turkey
14 cups vegetable broth (7 cans)
1/2 gallon apple juice
1 cup kosher salt 
2 tablespoon crushed dried rosemary 
2 tablespoon dried sage 
2 tablespoon dried thyme
1 1/2 gallon ice water

In a large stock pot, combine the vegetable broth, juice, salt, rosemary, sage, and thyme. Bring to a boil, stirring frequently to be sure salt is dissolved. Remove from heat, and let cool to room temperature.
When the broth mixture is cool, pour it into a clean 5 gallon bucket (I used a big bag designed for brining from William Sonoma). Stir in the ice water.

Wash and Dry your turkey. Make sure you have removed the innards. Place the turkey, breast down, into the brine. Make sure that the cavity gets filled. Place the bucket in the refrigerator. Let sit overnight. Remove the turkey carefully draining off the excess brine and pat dry. Discard excess brine.

In bottom of pan, create roasting rack with celery and carrots (this makes for tasty gravy)

Cook the turkey as desired reserving the drippings for gravy. Bake turkey until internal temperature reaches 180 degrees.

Keep in mind that brined turkeys cook 20 to 30 minutes faster so watch the temperature gauge.