We have used the same PVP for years...and he watches the prices for me and reduces my rates if the drop is before the final payment.
I don't ever ask for upgrades after that since I select the cabin I am happy with when I book.
IF free upgrades are offered by the upgrade fairy, I consider them and make a decision at that time.
IF the Upsell fairy calls (meaning it costs more)....I usually say no.
We have only done one group cruise (Bloggers in Feb 2009) and got an excellent deal on that through a TA..... we will consider group cruises in the future when they are available.