Hi Zafiro,
I dined at 'Ohanas for breakfast on my last trip and my daughters were aged 10 and 12, it was actually their decision to go there. We all enjoyed it and even though my girls thought they were too old to join in the parade they both enjoyed meeting Lilo, Stitch, Mickey and Pluto (characters may change) and getting their autographs and photos. The food here is family style which your son would probably enjoy as all the food gets brought to the table and you just ask for more when needed. When we ate there we started with lots of fruit, breads and pastries and the most delicious juice, this was followed by eggs, bacon, potatoes and sausages and finished with Mickey waffles and coffee. You can view some details
HERE.
I've never been to the Rainforest Cafe for breakfast and the only one that serves breakfast at Disney is the Animal Kingdom one. It is very similar to other Rainforest Cafe's around the world with a jungle theme, animal noises, thunder etc. You can see the menu for this restaurant by visiting
www.allears.net clicking on dining then menus.
I'm not sure which to recommend for your family, maybe ask them if they'd like to dine with characters or not. My feeling though is that you can dine at a Rainforest Cafe anywhere whereas you can only eat at 'Ohanas in Disney. It also should depend on which park you'd like to visit that day, if you're planning on Animal Kingdom then the wise choice would be Rainforest, if you're visiting any of the others then 'Ohanas would be the best choice.
Have a great trip,
Jo