After painting and repainting our walls and still seeing the old color under 6 or so coats (and it wasn't that dark, it just seemed to absorb the paint like chalk), we decided to go with some expensive paint and headed to Gervic for Benjamin Moore. It was great! It was basically covered in one coat, but my husband did another for good measure. Now he always buys a top quality paint from Gervic.
I haven't found them to be great for specific recommendations (like what kind to use on a floor) and one employee talked my husband out of the color/finish I sent him in for, but they do carry good paints, wallpaper, stains, and the tools you need to get the job done. We haven't used their decorating services, so I don't know how that is.