IMO two points to be considered. Firstly suites can hold a lot of moisture (depending on whats underneath the cover) like carpets they tend to lighten as they dry - this can take a while. So it could well be some time after you've gone until it looks its best. The other point is surely, like carpets, furniture can wear so if its oldish it may well not look like new whatever you do to it.
For really grubby bits I've found that Hydramaster's product is pretty good - smells a bit but good at getting gunge off.