Thank you all for making me think, and think.
I always saw the triple lenses as a great option. Advantage light an sharpeness. Disadvantages: the cost, well yes it cost, but it is feasable to buy one item at the time. That is in part why I got the 14-24, knowing I would move to FX. But the weight. I am 60 years old and mostly take pictures outside and on trips, and carry the whole bag is not for me anymore.
So here what I thought after your comments and also seeing that great shot by Kanuck. I will get the D800 and the 70/300, and later may get the 70-200 (and shoot the street with one lens at the time, rather than carrying the whole bag , depending how I feel with the 70-300.
So thanks again to all. It really has been very useful.

kyoshinikon said:
... the 70-200mm has to be one of the best and most universal lenses ever made. About every pro has one (admittedly I own 80-200mm 2.8's) Nikonians,Canuts, and Sony shooters all have one...

+1
If you are looking at that cost as ok, 70-200 is "budder". Add the 1.7 or 2x TC (converter) and you will have your 300mm again. 24-120mm f/4 is a great walk around lens for the mid range if you don't need the 2.8. Or as Tcole said, add primes in the middle (that is what I use mostly.).

Both are said to be soft at the 200-300mm end and I have owned both. I am quite happy with the 70-300mm VR and was not impressed so much with the 28-300mm so I dumped it and eventually just shelled out for the incredible 24-70mm. Maybe I just had a bad sample? The 70-300mm VR is screaming bargain and is a great lens though. I got this shot with it:

Since you already have the 14-24 there are a couple of choices then.
28-300, all in one and will have similar performance to 18-200
24-120 & 70-300, multiple lenses probably overall better performance than the 28-300
50 prime & 70-300, will be missing some focal lengths but the 50 will be sharp
50 prime & 70-200, expensive but better performance...no 300 mm
24-70 & 70-200, would complete the "trinity" but very expensive although best performance through the focal lengths...no 300 mm

If you just want a general purpose lens like your 18-200 then the 28-300 would be the obvious and only choice really, but just keep in mind the performance will be fairly similar to the 18-200. Depending on your budget the 300 F4 I have heard is great and would be a good pair to the 70-200.

Im a sucker for fast wide lenses (like the 14-24mm and 17-35mm which I both use) but the 70-200mm has to be one of the best and most universal lenses ever made. About every pro has one (admittedly I own 80-200mm 2.8's) Nikonians,Canuts, and Sony shooters all have one...

First of all thank to all for helping and yes Tcole, that is my dilema.
I did already get the 14/24 mm, to oblige me to shoot wide as my eye sees everything in zoom. But if no new lens shows up with the D800, I will most probably follow your advice and get the 70/200. And by the way I already enjoy the new lens, and will surely enjoy it more with on the right camera.

I am not necessarily sure you are 100% correct in your thinking. You are going FX, but you are buying a lens that will essentially perform like that of the 18-200. I don't really think you will find any sharpness improvements with the 28-300 and you might with the 70-300 up until around 200 mm where I have heard it falls off...as does the 28-300. The 28-300 has its downfalls as does the 18-200. If you wanted an increase in sharpness personally I would recommend the 70-200.

The 70/300 is a bit soft on the long end but sharper than anything else in the range.
both would probably perform about the same as you really need to stop down to f/8-11 for maximum sharp results.

If you like the 18-200 - personally I would suggest going with 28/300 - same range you are used to.

That said, if you are pixel peeping for sharpness, your best bet is to go with a couple 2.8 lenses with less zoom or with primes. Doing a quick analysis of what focal range you shoot most would give you the best idea where your money should go towards - long, middle, or short if you go that route.

I can't give you experience on the 28/300, but my 70/300 is a little too soft at the long end and or used wide. Great for the money though.

Generally the wider the zoom range the less good the performance, so I can't logically see the 28/300 outperforming the 70/300 overall.

Not much help.

Hi

I have been very happy with a D300 and the 18/200 lens.
I have taken the decision to switch to full frame, as I wish to have more sharpness.
I like the range of a 28/300 but was wandering about the difference in quality with the 70/300.
Thank you sharing your experience and advise me.
Gado