To see what they're going for, I'd say to look up each issue on eBay and it'll give you an idea of how much they're going for. Needless to say, the condition will matter (especially since guys buying that era of comics will probably be OCD about it).
The easiest thing would be to sell them as a lot to a dealer but if you want to maximize your profit, I'd sell them individually on eBay. Set the price low (like a buck) and take what you can get. It'll make you more money than it would sitting in a box. Of course, the same could be said about selling them as a lot to a dealer and saving yourself the headache of eBay.
And if you've got a copy of Amazing Fantasy 15, it's not worth anything but I'll give you $5 for it.
