A FlyerTalk Posting Legend
Join Date: Jul 2002
Location: MCI
Programs: AA Gold 1MM, AS MVP, UA Silver, WN A-List, Marriott LT Titanium, HH Diamond
Posts: 52,575
I personally value the 2 Cat 4 free nights as being roughly worth 25-30k assuming I can find a very good use for them. In a case like this, I'd just bust 'em a call, make the switch, and be done with it. (Or switch to a lower, other Megabonus if you truly have no need for Cat 4 Free Nights in Spring '11.)
Your points gain by spending more money on unneeded rooms isn't going to be worth it.