Between April and May. If your local IMAX is playing nothing but Beauty and the Beast for 100% of their showtimes, it's last day will be April 30. If they're sneaking in other movies into the mix as time goes (as mine is) they will be holding it until mid-May.
Call your local IMAX to find out what's going on. A word to the wise: Beauty and the Beast has been doing less business during the week than Fantasia 2000 did since it has a younger audience, and the kids are in school during the week. If you want to avoid any crowds, go on a weekday and you'll have your choice of seats!
I called the closest IMAX theater playing Beauty and the Beast , which was Memphis, Tennessee. They told me it would play through May. My girlfriend and I attended a 1:00 Wednesday showing a few weeks ago and were the only ones in the theater.
If you haven't seen it yet, it's well worth the effort to get there. I went to Atlanta this weekend to see it and was just floored by how good it looked on the IMAX. I saw Fantasia 2 in Baltimore and though it was great, but BATB was far beyond.
The opening scene with the stained glass window and the Ballroom scene were just spectacular. It never looked anywhere near this good on the regular screen. It wasn't widescreen, but I know it wasn't real wide to start with