There are lots of HHonors choices in the area, and true bargain rates can be had on weekends. The D'tree Marietta is acceptable, if maybe a bit tired. It's a full-service hotel (ample buffet; free cold selections for Diamond) but I would place construction date in the early 80s.
I will second the recommendation on the D'tree Suites Galleria. If it matters to you, specify an outside-facing room or risk windows onto the atrium.
Just another mile or so distant is the ES Galleria. I have no use for CRT TVs at this point, but otherwise this is well-executed and -maintained example of the ES brand.
My visits all occurred within the last month.