Hmm I think SMSM is tiered at 3 days, 5 days, then 7 days. So with 4 nights you're paying the same rate as someone staying only 3.
At PBH with summer rates you might want to check out the Annual Pass holder discount (it's not out yet, you could get an idea by looking at last years threads) the AP discount for the hotel might save more than either the AAA or SMSM.