There is now a "cruise exchange" option on II that I have been playing with. I have been looking at a cruise in April 2010 for dd's wedding. The rates from Vacationstogo and II are very close.
I went through the whole process to where II was asking for $$. I do NOT have a gold membership and the exchange fee was either included in the price or no exchange fee.
Bottom line, using a unit with a $400 maintenance fee the interval cruise was $78 less than the one at vacationstogo. So no great deal but I still have my AC in addition to use and have to pay my maintenance fees anyway.
If you have a low $$ maintenance fee, it might be close to a cruise discounter and like many here I have more weeks than I can use.
Can you chose your cabin and location with the cruise exchange?
The last time I talked to II regarding a cruise exchange (years ago), I got the impression they took your unit, booked the cruise and assigned you a cabin.
I don't remember the refund policy (if any).