I wouldn't want to stake the farm on either Goldman Sachs or your brother. Quite honestly, no one knows for sure what will happen....its all speculation on both sides.
We went ahead and purchased most of our large expenses (flight, tickets, owners fees for our resort, etc.) now partly because some were actually due (like our owners fees for SVR) and partly because we were totally okay with the rate as it stands now. If our dollar strengthens, we will go ahead and sit aside the remaining cash we want to have on hand for shopping and dining, taking advantage of a better rate for our final vacation costs. If it drops, then we can pat ourselves on the back and congratulate ourselves for our forward thinking

knowing that the biggest expenses were covered before the dollar nose-dived.
Our first trip to Orlando was in January 2009, and I think our Canadian dollar was at about 70 cents US then. So even 90 cents seems pretty decent in comparison.
My DH works in the auto industry, so a low Canadian dollar means better profitability for the company he works for. We always try to keep that in mind when our dollar declines.