Hi Adamak
On Skye, there is quite a big range of easier walks on this website (see the
Isle of Skye section; it's a great island for moderate walks though many of them are very boggy so bring suitable boots!
The Suisnish - Boreraig circuit (Broadford area) is a bit of a classic amongst low level routes and isn't steep, however it is pretty long and tiring so the kids would have to be very fit! In my opinion everything on Raasay is also very good.
If the ascent of the Storr is a bit too steep, it is still well worth doing the walk just up to the Old Man, the pinnacle below it, and exploring the area around that. This is a pretty unmissable place - one of the most spectacular in Scotland - but also very popular. The Quiraing further north is another really classic short walk; again to make this easier, just follow the main path across the hillside (one awkward rocky step requiring care but you could probably help the kids across it) to see the Prison and the Needle; again you won't lack company.
A personal favourite of mine is Rubha Hunish; again you can omit the trickier part of the walk on this site that descends the cliffs and just visit the old coastguard lookout instead. If you've got binoculars there's no better place to watch for whales and enjoy massive seascapes. Waternish Head is another fairly simple one but good views out to sea.
Shorter, easier walks include the Coral Beaches near Dunvegan (nice n' easy, lovely beach but quite a busy walk), Scorrybreac circuit at Portree etc.
[Time for a shameless plug] My wife and I are just finishing writing a book of moderate walks on Skye which should be out June-ish. [end of shameless plug]. Most of the routes are available on this website though.