The OE suspension on some bikes is a bit budget. Even that on the FZS1000's is considered to be getting soggy by10K.
I am just in the process of sorting the suspension on my VFR (see my other posts) and have gone for a Hagon shock. I took the opportunity to strip and clean up the back of the bike as is has clocked up 40,000 miles. It should be finished by this weekend and at some point in the next few weeks I'll start on the forks. (New springs, Hagon again, plus seals and oil)
How far you go with yours depends on what you want to spend and how you used the bike. Some OE rear shocks can be rebuilt and improved upon in repsect of the standard setup. You can also go the budget route in terms of replacement (ie Hagon) or you can push the boat out and spend a fortune on something like Ohlins.
Similar can be said of the front forks although in most cases a rebuild and new springs will give you good results.
My VFR is used for touring amoungst other things and although I have aimed for a result that will be better than the OE setup, there is no point is spending a lot of money on racing kit.
Normally I would suggest taking your bike to a suspension specialist and asking them to set it up before you spent any money on replacements/upgrades, but, as you have mentioned that there is not much adjustment available, this may not make any difference.