+1 for kids being wowed by planets more than black&white! DSO (no colour vision during the night).
in case you haven't come across this during your research, here's a calculator to give you an impression of how an object like a planet would look like in the scope with eyepiece you are considering.
https://astronomy.tools/calculators/field_of_view/
aperture is important. but for planets, it's about (long) focal length of the tube and magnification via eyepiece.
I would not buy "any entry refractor" like wavytone suggests. The wobbling mount these come usually with would destroy all fun immediately.
Speaking of the mount, Goto capacity would be great, too.
Alt-Az Goto mounts are easy as pie to set up for an adult newbie.
and it'll keep the planet in the field of view even if the kids take 20 minutes to fight about who's next at the eyepiece.
a mount like this with wouldn't be a bad choice.
if you were to chose this complete setup: plus an additional barlow so you'd get to the magnification needed for planets when using the 10mm eyepiece:
http://http://www.ebay.com.au/itm/Telescope-1026-GOTO-Saxon-Reflector-/361287509441?hash=item541e69e5c1:g: WuwAAOxy4fBTlCqd