For a bed quilt, you can either make a generic size or you can find out the specifics of how and where the quilt will be used. Does the bed have a footboard, and do you want the quilt to be tucked behind it, or just come to the edge? How deep are the mattress and the box springs, and do you want the quilt to cover the box springs as well as the mattress? Do you want a pillow tuck at the top? All of these can affect the size of the quilt, and so there's no "normal" size for a bed quilt. For any other quilt, I agree with ckcowl - customize it to the size of the recipient. If in doubt, make it larger. A quilt that is too large is better than one that's too small, IMHO.