I've been to Vegas 5 times I can honestly say I have NEVER seen a hotel offer breakfast as part of the price. I have only stayed on strip so can't comment on any off-strip hotels as I don't know.
Their are, however, LOTS of places to have Breakfast on Strip...From your Grim MacDonald type McMuffins, onto Dennys and the Like and then onto the All-you-can-eat buffets in most of the boutique hotels.
These All-you-can-eat aren't as cheap as you'd expect (start at about $12)....but treat yourself to the Breakfast buffet in "Paris" whilst your there....Fantastic!!!!
Enjoy your trip