I've always enjoyed
Nina, and really I don't think it's nicknamey at all. All the Ninas I've known have been just that -
Nina. It's got a light, dancing quality about it that I really like. Sunlight on moving water.
I think
Nina Margaret is wonderful and by far the nicest on your list.
Elizabeth works well ... or you could go for retro playfulness and have
Nina Lizann! Two for the price of one ...