The Amelia Concours was purchased by Hagerty earlier this year. That being said, there is now new leadership, so it may be different than prior years. I suspect Hagerty will do a great job in the long term, but as this is their first year running it, it will be interesting to see how the initial transition goes.
In general the main Concours event is all day Sunday. There are lots of auctions and smaller ancillary events around it, from Thursday till Sunday. Gooding, RM, Bonham's, Porsche Club etc... In general, I have always enjoyed the Gooding and RM Auctions. They typically have really nice inventory. I believe Bonham's has a few special cars this year too. There typically is a Cars and Coffee type event Saturday. Usually some nice cars, but nowhere near the caliber of Sunday's event.
We went last year and really enjoyed it, lots of events besides the actual concourse. Also sold my Rolls Merlin at Bonhams, which was my first-ever traditional auction experience. They treated me well and the car met reserve. Having to give it a miss this years for various reasons