What made you choose Bodoni Poster in the first place?

How about Elephant and Elephant Italic?

http://www.fontonic.com/download.asp?id=2006

I didn't choose bodoni poster... was an existing font in use by the company I'm working with. But, was looking for something that has a similar style but a bit more readable at smaller sizes.

Well, if you're after the boldness and high contrast you might want to take a look at this collection.

Hoefler & Frere Jones's Didot with optical sizes is also worth a look.

There's also Leitura and Leitura Display by Dino dos Santos. It's not a didone, like Bodoni, but it has a rather high contrast and the display cut is very expressive.

I'm a sucker for Bodoni Egyptian (predominantly for text), by Nick Shinn, which would pair nicely with most other Didones.

Don't know if this is close enough to Poster Bodoni for you (or bold enough), but speaking of Nick Shinn, his Scotch Modern has a nice display cut, but also a text size and even a "micro" cut that seems very readable even at seriously small sizes.
http://www.shinntype.com/scotch.html (check the PDF)