Well, depending on how you do the math, you didn't take it on the chin that badly...
The S&S deal means buying $120 worth of stuff ($100 GC + $20 groceries) for $100 for a 16.7% discount. If you factor in that the deal is limit 1 per transaction, buying $2,000 worth in one trip would have irritated everyone behind you and/or brought the manager over to stick his or her nose into your business, possibly limiting you. THEN, redeeming the $20 coupons are also 1 per transaction, so that means breaking up your groceries into multiple purchases, possibly multiple trips. At the end of the day, you have to work pretty hard for that extra 3-4% when all you had to do for the BJs deal was put through a couple of online orders. No gas or serious time investment involved.