I'd love to buy SSFIV for launch, but I'm pretty burnt on fighters. I played SSFIV, BBCS, and MvC3 back to back 
Did they announce a Layton release? that would be a perfect launch game for me, other than that I'm mostly looking at some missed DS game. Don't ask me why I'm buying this day 1, I'm just gonna.
My reasoning is that I know I'm buying Ocarina of Time in June, and I don't think this thing is going to get much cheaper in ~2 months.
I want Pilotwings and that's what I'm buying, but it definitely sounds disappointing when it can be finished in under 3 hours (as in, 100% everything). And apparently the way pad the length are collectibles that extend the time you can play. So, yeah. That for $39.99

I'm a terrible consumer, or a great one, I don't know anymore.
(That's just my reasoning. It's really because I like getting new hardware to play with. I don't own every iteration of the DS and PSP (sans DS XL) because I'm sane.)