First of all congrats on the weight loss.
Marshalls, Ross and TJ Maxx are incredible for casual and business casual. I would ask them when they get their shipments as well. If you get that info you can time your shopping to get all of the best stuff before it's gone (and it will FLY off the racks). I got lucky once and was there RIGHT when they put in what seemed to be an entire truckload of Brooks Brothers items - everything from dress shirts (formal to business casual), sweaters, coats (including a 3/4 length trench), sports coats and even suits. The amazing part was that all the stuff was from their golden fleece and/or 1818 line - not the "346" which is essentially the budget line.
Nordstrom Rack will have decent suits at times. But honestly with suit you'd do more than fine going to Joseph A Banks and ensuring the suit is tailored to your measurements. The old adage is true - better to have a $300 suit that fits perfectly than a $1,500 suit that fits poorly.