Star Wars Weekend at Disney's Hollywood Studios is a family tradition & last year I was in a similar situation. When I found out about the STAR WARS Dine-In Galactic Breakfast! at Sci-Fi and Jedi's Mickey's STAR WARS Dine at Hollywood & Vine, I was incredibly excited and wanted to book them both. However, I realized it wouldn't be in our budget to do both.
To help make up my mind, I started doing lots of research on other guests' experiences by looking at independent websites like The Disney Food Blog, AllEars.Net, DisneyTourist Blog, and Touring Plans.
Since my children are older, we ended up going to the breakfast at the Sci-Fi Dine-In Theatre since I knew they wouldn't be scared in the dark (practice with camera beforehand!) with creatures like Greedo, Jawas, & Stormtroopers sneaking around & being mischievous. It isn't scary, but Greedo has long green fingers and may try to steal your food. For a little one, that could be frightening. It was also good for us to do the dining early so that we would then have the rest of the day to enjoy all the Star Wars events. The breakfast is a fixed menu with several courses and options; it is all you can eat, and we all enjoyed our meals and even tried some blue milk!
The Hollywood & Vine experience, I believe, is great for all ages & not as intimidating if you have a little-one who might be scared. It can also be a nice break at the end of the day, but right before the special Star Wars themed-fireworks (which have not been announced for 2015, however). The dinner is a buffet, so many choices with Star Wars theming and much better lighting for photos.
I hope this helps you in your decision; please let us know if we can help again if you have further questions.
May the Force be with you! -Kara