While I think @jpkota provides a workable answer, I wonder if maybe your worrying too much. Provided emacsclient is working OK, there is no problem with having multiple emacsclient sessions running at once - in fact, it is sort of designed to do that. The emacsclient connections are light-weight and if there is a chance you might need to use the same file/buffer again, you may as well keep them around and just open new ones when needed and get rid of the ones you don't think you will need. The whole benefit of emacscleint is that opening new windows/buffers is really fast and if you use the GUI verison, they just pop up in their own window.
There is also a package in elpa which may be useful called osx-pseudo-daemon, which addresses a problem that can occur if you close all emacsclient windows which prevents the main emacs from responding (this is when yu run emacs from launchctl.
What I tend to do is run emacsclient in GUI mode rather than inside a terminal. When I run emacsclient I put it in the background so that it doesn't block my terminal and use the -c flag.(I actually have a shell script which makes this easy - see http://emacsformacosx.com/tips for some ideas. I leave the emacsclient window open and just switch to it if I need to do some emacs editing etc.