I love the Nikkor 70-300. I have a $100 G, which is pretty much the same optics as the $250 ED
but without an aperture ring, which is not an issue on the D70. Stopped down to f/8 or 11 it can give more expensive lenses a run for their money.
I would avoid a 28-300 zoom like the plague because a) optical quality with that zoom range is what it is, i.e. not top notch and b) it's not really a wide angle at the wide end because of the 1.5x factor of the D70. You'd effectively have a 42-450 lens and 42mm isn't wide enough, at least for me.
My 2 cents is: get a Nikkor 18-70DX and either 70-300, spend $500, and Bob's your uncle.
If you are bent on getting a good long lens, think about a Nikkor 300/4 -- it's $1,000 new, you can probably find one used for an approachable sum and you've got yourself a 450mm beast on your D70. And you can add teleconverters without much loss of quality.