Two things. Suites are not included in the upgrade benefit. There are no upgrades guaranteed at Residence Inn (or Towneplace):
Free Room Upgrade: Suites not included; based on room availability at check-in and limited to a Member's personal guestroom. For Residence Inn and TownePlace Suites, upgrades from Studio rooms to 1- or 2-bedrooms are not guaranteed. Not available at Marriott Vacation Club.
You have been the beneficiary of the hotels in your recent stays going "above and beyond". Nothing wrong with that - but remember that the suite and RI upgrades you've received are not officially part of the program.
In general, if you call/fax/e-mail ahead and let the property know an upgrade is important, you're more likely to get it. Most properties want elite guests to be happy, even if that means going beyond what is required.