Comfort Suites:

Usually found these very good, with refreshements in evening and a hot breakfast.
2 in Charlotte - Very good - but slow front desk.
1 in Greenville, SC - Very good, excellent refreshments
1 in Columbus OH airport - Good

Comfort Inn
San Antonio (East side) - Very Good
Moline, IL - Good

I too have found many Quality Inns to be only fair, on average.

There are lots of differences in properties - which is normal for mid tier hotel chains.

I find:
Comfort Suites - very good quality

Comfort Inn - good

Sleep Inn - smaller rooms and not as good as Comfort Inns, although clean and efficient.

Clarion - not much experience.

Quality - The most inconsistant of the group.
Have had some really poor experiences.

Awards for free rooms: Very easy to get by a phone call (same day ok) and many properties even in smaller towns.
Beware: Choice Frequent stay credits are not automatically enter into system. They call or fax info in (which I have found to be about 80% reliable). So check your stay credits.

Also: No on line statements and only occasional printed statements.