Dax,
to IIS!
While not often thrown into the mix of normal first telescope suggestions here, even by me, I would suggest a different telescope for your 6 year old. A small refractor!
I have recently been involved with the very same situation as yourself - a family with littlies and a choice between a small refractor or a small dob (not even an 8" dob in this case!). We decided that for all practicalities that a 70mm refractor would be a better choice for a little kid.
Don't forget that a 6 year old may actually not reach the eyepiece at zenith with an 8" dob - a small step ladder is neither safe nor practical long term here. And an 8" dob can be an unyielding beast at times, needing a bit of brute force when close to zenith too. And from a pointing stand point, a refractor will be much easier to understand the spacial geometry involved with relation to the sky.
I am all for aperture being King! But we can forget sometimes that adults do not have the same physical limitations of a child. Sure mum and dad can help, but the help is wanted only so-far, as a kid will still like to have some independence in becoming familiar with a scope, especially if it is THEIR scope - sorry mum and dad, but kids do grow wings early!
- I have two kiddies myself...
In so far as shifting a big 8" dob to the park, you'll do that once or twice, but then no more. A small 70mm refractor on the other hand is a much easier proposition. Your son can also be entrusted with carrying one or other component of the scope, but not with a dob.
A 70mm refractor is no slouch either! It will show you the rings of Saturn, the moons of Jupiter, some features on Mars, and plenty of deep sky objects. And let's not forget the MOON! Like you said, you
want to encourage, not overwhelm as an 8" dob I feel will. The pleasure and awe that will come with receiving a 70mm refractor will be none the less as great as a blooming big 8" dob.
We also forget that a Newtonian, of ANY size, requires much more maintenance. For a 6 year old, you want something that is always ready to go, not stuff around with optics that shift and need regular aligning, especially when transporting is necessary. The very occasional cleaning of the primary mirror, well, forget that too.
Storing a packed down refractor will be a whole lot easier than an 8" dob. It can sit waiting patiently for years, out of the way, waiting for the day that the sky calls again, and it will still be a happy reacquaintance with an old friend. A scope that will be happily be kept somewhere in the house.
If your son was 13, sure an 8" dob is feasible. For a 6 year old, smaller is better right now. Plus, for a 6 year old, a refractor IS what a telescope looks like.
Mental.