The women who are a bit towards the plus size also look forward to developing a fashion statement. She also has her busy work days as well as her casual days when she steps out in her business casuals.
A lot depends on her and the way she wants to step out in style. It is also important what the management would want the female employees to wear. Slacks and pants are worn by women these days but the suit is perhaps an old custom these days. The plus sized women usually take up a lot of challenge as their body types do not enable them to wear all that they like to.
She can choose from among the skirts and the slacks that are available in black, navy and khaki colors. This will match any sweater and these would not look clumsy on people anyway. Tailored pants would look good on women who are plus size and they should look into the availability of certain things at the store.
The slinky knit is of course not a disadvantage and the knit look come in spandex or polyester which is a lot roomy and with a lot of colors. These can help in being casual or dressy, the way you like and these can be paired with garments of your choice. These dresses are reasonably priced too.
At a very formal business environment, she should be wearing jackets, in khaki, black or in ivory. These can be boxy and tailored and they look good when they fall blow the line of the hip. A woman can look good in these when they are using dressy pins or colorful scarves.