Okay, here's my current solution.
I have my own classroom and usually get to class before the students (I have to unlock it and get things set up). I'm going to put up one of the attached slides so the students can see it when they come in and while they’re waiting for class to start. Some are duplicated for morning/afternoon classes. The first week I do this, I'll have to tell the students what's going on. But after that, I plan on it being passive instruction unless they have a question about it.
This accomplishes a few things:
1) I don't actually have to do a lesson on greetings.
2) Does a little bit of greetings everyday.
3) Shows variety in greetings.
The speech bubbles and text boxes are grouped. Also, the first slide loops. Found the instructions here: http://msmvps.com/blogs/tohlz/archive/2006/09/10/Looping-a-slide-with-multiple-animations.aspx
First, click Slide Show > Set Up Show.
Put a checkmark to Loop continuously until 'Esc'.
Now, Click Slide Show > Custom Shows.
Select the slide you are looping, click Add.
Click Ok and Close.
Click on the slide you are looping.
Click Slide Show > Slide Transition. In Office 2010, Transitions have their own tab.
Under Advance slide, put a checkmark to Automatically After. This will allow the slide to loop automatically.
Do NOT Apply to all slides.
Right click on the thumbnail of the current slide, select Hide Slide.
Now, you will need to insert a new slide just before the slide you are looping.
On the new slide, insert an action button.
Set the hyperlink to the custom show you have created.
Put a checkmark on "Show and Return".
Ok your way out.