If you are like me, you tend to think of jumpsuits as summer wear, but there is no reason why long-sleeved jumpsuits could not be worn in the fall or even the winter, since they give you a bit of added warmth. Longer length sleeves can sometimes really make a difference style-wise, and in the case of jumpsuits, they can turn what would be casual wear into evening wear. Of course, this would not apply to all models – some are simply not meant to be formal in a any way.
Three very different examples – I like the lace on the black one:
Long sleeve jumpsuits for women pictured:
Left: Body Wrappers 569 / 569XX Womens Praise Long Sleeve Jumpsuit, white
Middle: Allegra K Lady Deep V Neck Long Sleeve Sheer Lace Upper Smocked Waist Jumpsuit Black XS
Right: Amico Woman Men White Long Raglan Sleeve Striped Anti Static Overall Jumpsuit
The type of fabric that is used can make a big difference. Linen, for example is very much associated with casual garments. It wrinkles easily, but is quite pleasant to wear in the summer time. Cotton is also an obvious choice. But you may be looking for a jumpsuit that is more formal, and the fabric it is made from should convey that formality. You may want to go for something lacy, or something sheer and flowing, or maybe something silky. Of course, fancier fabrics present their own problems: mainly care and cost.