Key selling points for Storyline?

Hi Jamie! Here are a few answers you can consider:

The Short and Sweet Answer:

"Because of Storyline's support for Triggers and Layers, we will be able to develop courses that are more interactive and engaging.This can lead to an increased number of people who want to view our courses, and will also provide a better learning experience for our trainees which of course will increase knowledge transfer."

The Long Winded, Probably More Info Than Your Boss Will Want to Know Answer   (Points to bring up in addition to above):

• Storyline supports publishing to HTML5 and iOS (with the Articulate Mobile Player). This will ensure that we will be ready to implement mobile learning if/when our organization chooses to implement it
• Storyline will allow us to develop both soft skills courses AND systems simulations/demos since it supports screen/video captures (With view mode, try mode and test mode)
• Storyline comes with a library of characters and a selection of interaction slides 
• Storyline is very intuitive, so it will take us minimal time to get proficient with learning how to use the software
• Storyline is pretty cool and I'd really enjoy using it, and an happy employee is a productive employee! (Ok you may not want to say this one :) )

With that said, once Studio '13 is released, the gap between what Storyline can do and what Studio can do will decrease some. Studio '13 will also support HTML5/iOS output, and have characters, but it won't have layers, triggers or screen recording functionality. Engage '13 is also going to have 10 new interactions that look pretty neat. 

Here is a quick post I wrote up after attending the Articulate Studio '13 Sneak Peak at DevLearn this past October. A few people in the audience asked what the differences were between the two and I posted some of the answers that were given. 

Good luck!

In addition to the reply above, some of my favorite things about Storyline are:

• With the Variables feature I can create more customized feedback for user choices, and can show the user the course progress easily. With Presenter customized feedback requires many slides, and has significant limitations (read, more development time and less user-specific feedback)
• With the Variables feature you can also control user progress through a multi-lesson course, "unlocking" lessons as the user completes them in order. This can be faked in Presenter using multiple menu slides, but with Storyline variables the course is actually responding to the user's actions. 
• In Presenter, I found myself spending a lot of time checking/fixing navigation hyperlinks, and reworking the slide properties to ensure navigation worked properly. It would take me a lot of time if I added or deleted new slides. Storyline's Story View makes all this much simpler, and the time I spend on making the course navigation work properly has significantly decreased. 
• Some of my frustrations with Engage were the limitations that it has... In Storyline you can custom create any of the Engage interactions and have no limitations. (this does take more development time, but it's a trade-off for customization)
• States allows me to add dynamic features to a slide to make the look and feel of the course flashier and more current with today's web technology. My Storyline courses feel more modern than my Presenter courses were. 

I could go on and on, but those are some of my favorite things! I still love the Studio suite and prefer to work with both - each program has their place for different project needs - but if I had to choose it would positively be Storyline.