I second Adam's vote for binos to start. (I started with a 60 mm Tasco refractor, but let's call that half a binocular.)
With a pair of binoculars, they can spend many a pleasurable evening on a garden chair with maps learning the sky. There are plenty of sites online that list cool things you can actually see with binoculars and a little practice, like star clusters, galaxies and the odd nebula.? ?After a couple of months of using binoculars, they'll know the skies, they'll know how to find stuff, they'll have their expectations set, and their eyes will have learned how to see details at low light levels. And they'll know one more important thing: do they really love looking at the night sky--even when it's nasty cold or when the mosquitoes are out in force?
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If you were to start them with a larger scope, they might have the same experience as people I sometimes meet at public observing sites.? They've got a new scope, but they're frustrated, because they don't know their skies, and they can't find anything to look at besides the moon and some of the brighter planets.? A computerized Go-To scope--one that can find things on its own--will alleviate some of this frustration, but they cost a lot more than $300.? Besides, I have a friend who has what he sometimes calls a "Go-Near" scope. "Go-Near" because, when it's not aligned properly, it can't find anything, even though I still can. Maybe I'm old fashioned, but I think it's best to learn the sky first, and then use the machines to help you later. (I also walked two miles to school through waist-deep snow uphill both ways when I was a kid.)
Now, some would say that a pair of binoculars is not really a telescope.? However, for $300, you can get a good pair--a pair that will last a lifetime.? They'll need them for that long, too, because if they later decide to buy a scope, they'll still be using the binos to reconoiter the skies when they're seeking difficult quarry.
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Not only that, they may find that their lifestyle does not readily admit a "family" telescope. My wife >hates< telescopes. They take up too much space and too much of my time, she says.? Their first telescope may be like my third--a Short-Tube 80mm f/5 refractor not much bigger than a pair of binoculars that I hide amongst my wife's shoes.? Binoculars (like my ST 80, but not including its tripod) will be easy to take back and forth between the cottage and home because binos don't take much space.
Finally, let's talk about the worst case scenario: suppose they decide after learning the sky that astronomy is not for them. I think they'll still find the binoculars useful -- particularly at the cottage for looking at birds and other things (or in the city for spying on neighbours, not that I've ever been known to do that obsessively).?
But, if you're set on a scope, you can't beat a basic 6" or 8" Dob.?
yeldahtron