When you can find footy fleece sleepers (blanket sleepers), they're great cause the kids usually kick off the blankets, thus the tradition of tucking our kids back in when WE go to bed! But yes, a blanket is fine.
At 14 mo you should get a good supply of the sleepers at places like Carter's (try to catch sales). I found sleepers for my five year old at Target this year, 12 or 13 apiece. Not bad!
Y'know, mommyhood is stressful enough, especially with the first kid; if you're more comfortable tucking it in for now, I see nothing wrong with that. When your kid wants it un-tucked and can do it himself, then you can REALLY relax about it.
I like afghans because they're pretty hole-y and it's unlikely a kid would smother himself with it. And they're WARM! My kid still loves hers. Make one double strand and it's even toastier.
-S. Kav