Your best bets are Shaw for Nylon (typically more durable than polyester for super high traffic), and Dreamweaver for polyester (by far the best polyester carpet in terms of bang for your buck and stain resistance, but not quite as durable as Nylon. 

This isn't an area in which I have any expertise, but Google tells me that microfiber is a form of fine polyester.

We did some research and learned that hotels use sheets made of percale - a cotton polyester blend.

Cotton polyester blends are great for sheets.

Many clothes are polyester/synthetic that do not readily support mold growth. 

., dressed myself up in Polyester slacks and silk blouses, panty house (that were required), and high heeled shoes.

The fourth layer is usually made up of polyester material which can resist vapor from the subfloor and balance other 3 layers.

Examples such as the VCR machine, 8 Track tapes, polyester Leisure Suits ( Hmmm...that was random), to name a few.

. $1,500.I know the carpet needs to be replaced but is nylon good enough with a nice 8 lb. pad or do I need to go polyester?

Note on carpet choice...stay away from polyester, it will show traffic patterns quickly.