I would like to here peoples experiences with IVY official visits. What does such an invite mean regarding an offer/admission?

In my son's case it was the only opportunity we had to visit the campus. If your visit is similar to ours then:

Your son will be hosted by a member of the baseball team and will attend class, eat meals, sleep in dorm room, etc... with the host.

Your son will watch the team practice.

He will get a tour of the team & athletic facilities.

He will get a campus tour.

He will meet the entire team in a casual setting (watching college football on TV perhaps) so that the team can evaluate his personality fit for the program.

I endorse the idea that at least one parent should join your son on the visit. The coach will employ a 'divide & conquer' strategy as you & your son will part ways while your son hangs with the baseball team. I used my time to meet with the financial aid office, to meet & talk with current students at the library and student union, and to speak with faculty and administrative personnel in the academic department that my son intended to major in. (That didn't work as my son eliminated that major in his 1st term )

Take the trip. Learn as much as you can. Enjoy the experience.

My son is heading off to an Ivy for an official visit; offer for visit was made before his early admissions paperwork had been reviewed, but actual plans/reservations were secured only after Admissions Office gave thumbs up. It will be a quick trip, leaving Calif. Friday and returning home Sunday evening. His short time there will be spent with players/coaches and although there won't be any classroom visits, there will be a good glimpse at other aspects of college life.
He is excited because he is making the trip without Paps and Mom; we all saw the Ivy schools last summer on a drive through the NE states. We're very happy for him and anxious to see how he feels about it all when he returns home.