Enviable position to be in Nogbad.
My question is are you happy with the quality of the lenses you have and do they cover the range of your subjects sufficiently. You mention the 70-200 f2.8 VR IFED G Nikkor which sits in the same slot as your 70-300, hence the question.
Following what others have mentioned, then I have the 12-24, but wide angles of this nature are a bit of an aquired taste. If you rarely use the 18mm end of your kit lens then I would pass on it for now.
So although I have no experience of it I will throw in the AF-S 17-55mm f2.8 as an upgrade of the kit lens but then only if you use that a lot.
My real thought is that you go through your images and see the proportion at various focal lengths and then consider any weaknesses you feel in that area. ie if 300mm is used a lot and you do a lot of cropping then something to get you to 400mm is in order. If the kit lens is often used in poor light and you struggle to get to its optimum f8 without winding up ISO, then this is the weak link.
If you want longer reach than the 300 end of your zoom then you could think in terms of the 300 f4 and tc for autofocus. Manual focus a used 400 f5.5 IFED is highly recommended as that is what I have. But ...................... and there is always a but, your 190 legs are not really up to 400 and beyond. Not sure where in the Manfrotto range your ball head is either.
New hobby .......... virtual spending of other peoples money.
Don