I have write to say that we have returned from a weeks holiday at Periyali Villas at Zakynthos through Simpson Travel. We travelled with two toddlers (3.5yrs and 2.3yrs) and we returned and felt like we actually had a holiday!
Simpson's were amazing from booking until departure. The villas and the creche are perfect for kids and the fact that there are other families in the 'same boat' makes the experience so much mor enjoyable. The walk to the most lovely beach on the island is only approx 10 minutes and on the way are two amazing tavenernas (both with playgrounds).
I can't fault it and if you are looking for an amazing holiday for your family, please consider this venue - it was perfect.