@kathyjjb - my understanding is exactly what you stated regarding changing plans. I have a year and a half to go before I sign up but worked closely with my husband when he signed up last year. The advantage plans are what many of us see in the commercials. They offer low premiums and throw in or bundle some other benefits making it sound very appealing. The problem is if you later want to change for more options, there is an underwriting process so prior conditions will be reviewed making it much more costly if accepted. If you go straight into a supplemental plan, there is no review. The supplement plans do not include dental, vision and drugs so those are add ons. I believe the supplements are more of a PPO option while the Advantage is an HMO.