If your building an outdoor aviary I suggest this site:
NaturalBird.com Indoor and Outdoor Bird Enclosure FAQ
It tells you how to make a safe one and what you can do to prevent your bird from getting diseases outside.
This is painfully long, sorry:
Now onto the the Grey/Too question. My personal opinion, is the Grey. I never wanted another Too again - ever. I love Greys, Green Wings and Catalinas. I used to have a U2 years ago, that was the first large parrot I had ever had (long story but he was taken from me
). Fast forward to present time. I have never actually gone out and looked for a bird, stuff just finds me. I was offered my M2, free (she came with multiple cages, stands, toys etc.), on the way to meet her I tried to explain to my BF why I never wanted a Too, after meeting her we decided to bring her home. I have the right personality for a Too so in a way I sort of feel obligated to care for one seeing how there are so many in rescues. Toos are not easy to live with and require constant everything. There is soooo much to write about Toos that it would be ridiculous for me to re-type it all again. So I'm going to copy/paste an old post of mine below:
Owning Toos..... Hmmm, well they are different but completely rewarding if in the right household. Never get a Too and expect it to be quiet (this is not a realistic expectation) be prepared for one that screams all the time and be happy if you get one that doesn't. They are very sensitive birds, I like to refer to them as emotional basket cases - as well are the people who share their lives with them - thats right we are crazy. They sometimes require more time to transition into a new house hold. Give your new Too 1 FULL YEAR before making the determination whether to keep it or not (no matter how hard the transition may be to make) it can take that long to adjust.
Also I've copied and pasted the following from another post I responded to about Toos: They are loud (this is what def sets them apart). Usually they scream only when they aren't getting what they want (each is different, mine doesn't do any screaming regularly in am or pm. What people refer to the normal sounding off). When Rome first came home she went through a period where she wasn't happy anywhere - wasn't happy on my arm, she wasn't happy on her stand and she wasn't happy in her cage - no matter what we did she screamed. I waited for her to get over herself and shes come a long way since then but it was really really difficult in the beginning.
Its a misconception that Toos need 'more' time than other parrots because they don't. They act like they need more (when in actuality they really don't) so people give them more than what they need and they get spoiled (they spoil easily, I guess thats a better way to put it). Its not so much that they aren't independent (because they really are if thats the behavior that you encourage, but you have to provide them with the means to be independent, ex: they love to forage for food, so create an environment where thats what they do all day), its that they want more. You give them all the attention possible and they want double that (you give them an inch and they don't want a mile they want the entire country). Thats what we mean by demanding. This is why everyone throws the experience part out there. Toos are like a child, let them run the house and they will, however they thrive off of structure, routine, and discipline (with these in place you will have a wonderful Too). Look at it like the parents who give in when their child cries for a toy (these people should never own a Too, because the Too will end up owning them), a Too's scream is so loud that most 'give in' to what they want in stead of sticking to the rules. This only reinforces the screaming and makes the bird more in charge. The 'experience' that everyone talks about is the ability to not only reinforce positive behaviors but to also lay down strict rules and abide by them (i.e. a person who can be firm and strict makes a good Too owner). The fact is, that no matter what bird you choose to get your 'experience' from, may not set you up for a Too (I got my 'experience' from training horses - the concepts transcend into Too behavior). A Too constantly asks for attention, you cant give in to what they want. Attention time (when, what kind, and the length) needs to be set by you and not the bird (has to be on your terms - ALWAYS). They will beg and beg for attention, then they demand it, and you have to wait until they forget that they even wanted you in the first place, then you give them attention. They have to know that you set the rules and they have to know that these rules are firm. In the begging they will test the rules constantly. If you stay consistent then eventually the bird will learn and become better rounded.
Hope this helped, good luck in making a decision.