On a similar note, it's good to have a variety of foods in your pantry/storage also, so a variety of items each time you go would be better than all sugar today, all rice next week.
Ahhh, I miss Sam's club . . . 2 hours to get there isn't worth the membership anymore--I mostly mail order bulk items now, or hit case lot sales around here for flour/sugar/etc. And for the sugar, just tell them you make a lot of jam/jelly . . . shouldn't get any questions at 100 lbs at a time.