Hiya
I lived in Menorca back in 2003, and absolutely loved it (living there but not the working part
)
I'm also looking to go back for our summer holiday this year, either just with OH & DS or with a group of friends we went away with last year.
The resorts I am looking into are Cala n' Bosch, Son Bou and Cala n' Porter.
I only went to Cala n'Bosch a couple of times (as I lived on the other side of the island) but I really liked it, and the little marina was so pretty with quite a good selection of bars and restaurants. The beach was ok, but wasn't as nice as Son Bou or CnP. There is a little waterpark here, which would probably be suitable for your DC's. This is a flat resort as well.
Son Bou has the best beach by far and I used to go there all the time on my days off. There are a few restaurants just off the beach front and a handful of bars, but I wouldn't say the resort was as lively as CnB.
Cala n' Porter is only about 20 mins from the airport or so, quite a hilly resort. The beach is in a lovely little bay but it is an absolute killer to get down the 100+ steps in the August heat! There is a slope to drive down, but it's definitely not as accessible as Son Bou or CnB. I think this is probably the most "english" resort out of all 3 of them, lots of bars and restaurants here. Never went on a night out here but always wanted to because of the nightclub in the cliffs Cova d'en Xoroi which is also open in the day for a drink in. I can't comment whether the resort would become too Blackpool like in the evening, I can't imagine Menorca would be like that though!
You must make sure you include a trip to Mahon the capital, it's so beautiful and well worth going, especially on market days. 
I can't wait to go back!!