Marriott’s Q1-ish MegaBonus earning promotion is decent enough, I suppose, if you have a lot of Marriott stays during the promo period. And, generally speaking, earning hotel points for hotel stays is a better deal than going for airline points on those stays. But if you only have the occasional earning stay and would rather not orphan the points (or just accrue them ridiculously slowly) then crediting to an airline isn’t the worst choice out there. And thanks to the Mega Miles promo it can actually be a bit better.
The promo offers double airline miles starting with the second stay during the promo period (Feb 1 – April 30, 2013). Plus, the promo is valid for the nearly 40 airline programs Marriott partners with.