I have also done the "Cracker Jacks, Big League Chew, baseball cards, sunflower seeds route." I also added a blow-up baseball (looks like a beach ball), a baseball bat pen, and a hard plastic party drink cup that I all found at Party City. Then I got party bags in our city's Major League Team's color, printed out a large picture of their logo, and spray-adhesived it to the front of the bags. The kids really liked it and parents were all making compliments on it.
I have also gone the easy route before and given $5 Dairy Queen gift cards before to each party guest (kids only, of course!). As you can guess, that also was a huge hit with the kids & parents. My son's birthday is in the summer, so it was a nice time of year for it. By the time you buy the junk for all the kids bags I always ended up spending more than if I had just bought the gift cards in the 1st place.
Good Luck with the party and whatever you decide!