We have been to the Isle of Wight a few times, I have a Seven year old and a ten month old and have just returned.
Places I can recommend to see are, Blackgang Chine lovely theme park with enchanted fairies, pirate ships and reasonably priced. If you go on a Wednesday they have fireworks at the end of the night.
Godshill Model village is lovely and then a cream tea is a must.
They have a Zoo which we have yet to visit which is reasonably priced.
Sandown is very family friendly and the beach is sandy. There is a lovely pub on the corner near the pier which has lovely food.
Cowes is lovely for a spot of shopping, with shops such as White stuff, fat face and Joules.
In Ryde they have a lovely restaurant tucked away and the food is delicious
http://www.thebaygrill.co.uk/default.htm would highly recommend eating here.
Hope that gives you some ideas