I live in the city (of Abu Dhabi) but whenever I want to have a real breakfast (or any time of the day) treat, I always go to IKEA Restaurant as it is worth travelling for. The food is tasty, fresh, well prepared, planned and healthy but the price will not dent your pocket.
Should you want to go there while sight seeing, use the bus number 170, 180, 185, 190 for 30-45 mins ride. Fare cost 3-4AED (from Abu Dhabi Al Wahda Area bus station)--bus is going hourly.
Or better yet, go to Marina Mall and use the IKEA bus that travels to and fro hourly, ride is FREE!
(ok, to go to Marina Mall without spending so much for the taxi, use bus number 5, 7 and 11, fare is AED. 2).