We do ours "auction" style as well. By law, we cannot enter in to a storage unit that we processing. We inventory only what we can see. We do try to look around and take a mental note at that point of what is in the unit (mainly so we can publish it in the Public Notice's section of the newspaper). We have not done a sealed-bids auction. We usually have the same people come to each auction (most of the stuff shows up on ebay after it is removed from here) and they all are very well accustomed to the typical style. We start our bidding at $25 if we know there is not much in the unit. When we open it and the bidders can see it's nice furniture or such, we start the bidding at $100. I'm not even sure how a sealed-bid auction would work. Seems like more paperwork would be involved. And isn't there already enough with all the legalities???
I'd be interested in knowing how you conduct yours.