It will take less than a day to go round the whole of the isle of wight, so take it easy and do a bit at a time. If you have kids, take them to Black Gang Chine, quite a nice day out if the weather is good. Lots of walking there, things to see and do. Take a picnic dont buy food or drink there though, too expensive. Get the local tourist book too, its got lots of money off vouchers.