OH and I went 2 years ago last September. We stayed at the Canal D'Amour end of Sidari, not so commercialised but maybe a little better for those without children as it is very rocky (and extremely pretty) in parts, although there is a beach nearby and lovely shallow warm water, you can paddle out for ages and water is still only up to your knees . Good restaurants/bars further down in the town itself called "Sidari Strip" and lots of tourist shops (but some a bit tacky) but a great sandy beach in town suitable for families.
It is a lovely area, we hired a car, Fiat Panda, bit pricy at 170 euros week but well worth it, and visited Agios Spiydon beach on the Northern Coast but beware - the sea is a bit colder there due to the currents but good beach.
A fantastic place to visit at sunset is a few miles from Sidari, called Peraloudes where there is a very popular taverna perched up high on the rocks called the Sunset Taverna, they serve great meals, snacks and drinks here and it is packed with tourists during the evening wanting to catch a glimpse of the most amazing sunsets from the headland here.
If you want amazing tasty food which is mostly English (they do a fantastic Sunday roast!) look for "Churchills" at Canal D'Amour end of Sidari (English owned, all memorabilia round the walls about Winston Churchill) When we were there the owners played all 60s and 70s music and videos, and were such friendly people, so popular it was difficult to get a table most nights!
The weather in September wasn't brilliant, very mixed, quite a lot of rain. We stayed at Kalami further down the coast several years ago and that was in May, much better weather, very warm but with occasional thunderstorms. Kalami is also a beautiful bay, and nearby Kassiopi is a nice harbour resort with shops and good places to eat.
The Greek people are so lovely, very friendly, love their children and most speak good English.
I personally would not go AI, because if the food is not to your taste, you are stuck. Sidari caters for absolutely everyone and it is fairly cheap to eat out - we always go self catering so we care not stuck to regimented mealtimes.
We love the beautiful peaceful places in Corfu and keep well away from the "lager-lout" resorts! Enjoy your holiday jd, I'm really envious!