I've been thinking about buying a Lodge Dutch Oven for a little while now, but I just have one issue. I have NO idea what size to buy. Right now it's just me and the fiance, but we have a baby on the way. I don't want to buy a smaller size just to have to replace it in a few years, but I've never had a dutch oven so I don't know if it makes sense to cook smaller quantities in a bigger size. I'm mostly looking to cook pot roasts and stews and other beefy goodness, would you guys suggest a 3,4,6, or 7.5 quart dutch oven?