Hospital displaying my work.

[Tight Knot]

Hey Lyonsroar,
First of all, congratulations on your choice. It's people like you that help some of us keep our faith in Humanity. I agree with Tirediron that you could/should use this as a donation for tax purposes, that just sweetens the deal for you a little bit.
One word of advice for the zoo, is to ask the Hospital if they would write a letter on their letterhead stating that they have asked you to donate photographs for the childrens wing in the hospital (or just Childrens Hospital, if there is no wing) and that they are asking the zoo for help in allowing you access to some of the smaller, younger animals to photograph, and in exchange, each photo that they hang up that was taken at the zoo, will have the zoo's info on the painting as well, giving them free advertising, and it may even be classified as some sort of tax write off as well for the zoo for whatever fee they would charge for exclusive access (as a donation to the childrens hospital).
Just my 0.02c.
By the way, not sure if you want, but I would allow you to use some of my animal photos as well if you would like, (without using my name, I don't need to see it in print, or get recognition for it, although I would still hold ownership etc. of the original). Just PM me if you would like. (maybe not many, maybe not great, but the offer is there anyway).