planning a trip with 2 teen/college age daughters for a long weekend(daughter in study abroad in Beijing)
looking for shopping ideas for pearl and gem jewelry, antique jewelry, cashmere and any other favorites you might suggest.
also, need a Marriott Hotel in the heart of all of this.........thanks!

The best located Marriott IMO is the Shanghai Tomorrow Square. There is also a new Marriott Executive Apartments located in -- which might work very well for you as they have 2 bedrooms and kitchens. The location is pretty good.

As for jewelery and cashmere I can only say (i) do a good bit of comparison shopping before you leave so you know what prices are at home, this is the only way you are sure of getting a bargain, (ii) see a lot of real pearls and real cashmere so you can tell the difference between real and fake, and (iii) be very wary if the price seems too good to be true, as it probably is. Fake pearls and fake cashmere abound in China, be very very careful. I personally assume it is all fake and buy accordingly. I would not buy anything that is sold as "real" unless I had a Shanghainese speaking local friend with me. That is just me after 20 years in Asia, others are more trusting I suppose. I have officially become my Mother.

Sorry, the new Marriott Executive Apartments is in Pudong, I wanted to look up the address on their website, but posted too early:

Marriott Executive Apartments Union Square Pudong
506 Shang Cheng Road Pudong
Shanghai, 200120 China
Phone: 86 21 28998888
Fax: 86 21 28998866
http://marriott.com/property/propertypage/SHAUS

I can't remember anything of the kind in Shanghai but I would warn you against China in general. Watch out for fakes.

We were in Shanghai for 2 weeks last May and the only thing I bought were 2 pairs of ballerina shoes at Suzhou-Cobblers
(web site Suzhou-Cobblers.com)
and I only wish I had bought more! They are gorgeous and $60 at the shop as opposed to $120 on the web. Hand made, fabulous hand embroidered patterns, beautiful silk, and extremely comfortable. The shop is conveniently located on Fuzhou, a small street off the bund.

$60 for shoes is pricey in China, but they compare beautifully with Manolos, Choos, or Louboutins at $500.

I went to a jewelery mall located close to Chénghuáng Miào (Temple of the Town God). The mall has three levels. The top level consists of a lot of pearl shops. I bought a trend of pearl for my mother in law and several pair of earings.

The key is to walk around first and find out a general price there. I walked around couple of times and determined and size and quality of pearls that I was looking for. I would go 1/3 of the price they are asking to begin the negotiation. If you cannot get what you want, just walk away.

For jade, go to the same building Ghengis went to and visit Old Temple Gold Jewelers (lao miao huang jin), it's on the 1st and 2nd levels, the better stuff is upstairs. Very reputable.

topping for Marriot info, thanks 'again' Cicerone.