As good as the .30-30 is, the stocks are poorly designed to absorb recoil. The Winchesters are worse than the Marlins but they both have a higher "percieved" recoil than what it actually is. Yes the .30-30 is an option but in my opinion, not the best one. The 6.5 Swede and even 7mm Mauser that NoMercy mentioned would also be excellent choices. Also check out the New England Firearms rifles. These neat single shot rifles do come in .243, .25-06 and a bunch of other great deer calibers plus you can buy optional barrels in other calibers just like the Encore just a lot less expensive (they sell for around $200-$300.00 with extra barrels less than $100). They are also very accurate.

Regardless of which gun you buy the real problem will be making a decision because ther are so many good calibers for the kids. Pick any of them between .25-06 and 7mm-08 and let budget, stock fit, and ammo cost and availability be the deciding factors and you will be very happy.