A number of years ago, I too took the plunge with a student discount on CS4.
I have used photoshop, fireworks and dreamweaver the most. I like the freedom to sit and play around with concepts as a stress relief. Stuff that may not be commercially viable, but I want to explore.
Some stuff ill go the whole way and get ready for the printers, others, ill pass on the button to a designer to fine tune and do the fine end stuff that I'm not adept at.
I haven't really played much with ai, but I should probably explore it more. I usually prepare all my YP type ads myself and often get results I'm far happier with than getting their design guys coming up with stuff that is 'dime a dozen' approach.
Recently, Adobe released an older version, I think CS3, for free. I think it was only the academic version but honestly, unless you're making a living off it, you won't really know the difference. Google it, you may find it and takes the sting out of buying the current up to date stuff and at least you can decide if its for you or not. If it is, then take the plunge and buy the current suites.
John