Depending on chain, i.e. HIX, Residence Inn, many lower tier properites already provide free breakfast so that benefit is a bit illusory. As for upgrades, does it really matter at a Hampton, v. an inner city Westin where the difference could be a quiet room with a view v. a dark hole next to an elevator? And for 1 night stays I'd bet the 4pm checkout isn't worth to much - as most of the time that means flying in the night before an early meeting, and then straight to the airport to get outta dodge.

To me, all the lower end Hilton, Marriott, SPG, IC and Hyatt chain properties are a dime a dozen - there just ain't much difference between any of them and all provide free internet, breakfasts, etc. For that reason I think you would be better off looking at maxing the potential awards from one night stays (though apparently that isn't your goal). For me that would mean taking advantage of Hyatt's FFNs (or whatever they renamed it) and similar promos from SPG and Hilton that will get you free nights to use for leisure.