Why do you want to join a Fortune 500 company if you're not looking to climb the corporate ladder? You can find similar pay and more relaxed job environments at a smaller company. I find the bigger the corporation, the more rules and restrictions you have.

For instance at a small company I can be a sysadmin with many different hats and the job stays exciting longer because you can see the work all the way through. At a larger corporation you may be limited to one very small aspect of the network, there won't be much work to keep you busy and you'll master it quickly. Then the days will consist of trying to look busy even though you're bored out of your mind day in and day out.