This is obvious enough that I assume the answer is "no" -- can you get more gift-bag goodies?
If not, another thing you can do is to get a certain number of goodies for everyone (as in, go out tomorrow morning and get six [?] of whatever cheapo interesting things you can find) and then make the current goodies be grab-bag treats or prizes -- as in, break them up into roughly equal groupings (one G.I. Joe equals 4 toy soldiers) and then make six [?] "prize" bags. Then have a big box or something and they can grope around in there and choose one.
It's always a risk to give kids different things and even riskier if you go the prize route instead, in case one kid wins a bunch of different games.
Oh hey you can have a store! This takes some doing but you could do it. Make money. (Mo money.) Price goodies a certain way so that a kid can only afford to buy 1/6th (or whatever) of the loot. Then they decide what they want the most.
Put out a lot of food and other stuff they can buy too. Give them "shopping bags" to put the loot in. (Those become gift bags.) They can decorate the shopping bags for an activity.
A bit scattershot sorry, I'm rushed and need to turn off the computer -- more tomorrow!