I try to avoid Day 1 purchases as much as possible. The ones I got this gen are:
Super Street Fighter IV - did not regret buying, only purchased day 1 as it was released with a discounted price. I had been tracking SFIV for quite some time.
Gran Turismo 5 - bought under the impression that it would take ages for this to drop price. So far it has worked out this way.
I also got FIFA 11 as a gift. Would not have bought full retail myself.
and that's about it!