How to nicely quit a job I have been at for 10 years?

I have been at my current job for 10 years and was recently offered a great job with a different company. Currently I work with a small staff that is very dependent on me. How do I leave without upsetting and offending people I have worked for/with for so long? I do not want to burn any bridges and want to leave as gracefully as possible. I thought I would give four weeks notice. Any other suggestions?