Originally Posted by ALpolyman
How are poly relationships supposed to grow with such little availability? How fair is it to the person(s) we are dating?
How can any relationship grow with little availability? Having more relationships does create a scarcity of resource where available time is concerned, no way around it. There are a lot of definitions of what 'enough' time with another person constitutes, but you'll have to figure it out for your situation as you go forward. I would suggest you consider what you're both looking to gain, and what you're willing to give up to form new relationships with others.
Your relationship with your wife will change if you proceed down this path, and how you manage time with each other will be a big factor in whether its a positive or negative experience. Bad experiences often happen for a simple reason: the pre-existing relationship neglects quality time with each other and focuses on providing it for the new one. Eventually enough distance develops and problems occur, sometimes resulting in one partner dumping the original relationship to develop a monogamous relationship with the new partner.
Anyway, your question is anything but trivial. And that you're asking it up front bodes very well for you. Good luck, and go find the specific answers for yourselves (only you two can really address this question satisfactorily).