I need a recommendation of which app to use for creating slideshows. I'd like to add typography over some of my photos as well as music. I'm very experienced in Photoshop and Illustrator if this helps.

Try something different: Photodex - Create photo and video slideshows with ProShow

I use it quite a bit and it does what you might require. Note: I am not associated with the software - I tried it and it worked for some of my uses.

Premiere Elements or Premiere Pro for the editing.  After Effects for the typography if animated.