We are going to Bangkok in July with our two children (7 & 3) and plan to stay in Bangkok for a week before heading to Phuket. In Phuket, fortunately, we will be able to use our Mariotte points and that will cover our stay for 5 nights at the JW. Now we still have to work on the one in Bangkok. Does anybody have any tips on any current promotions / discounts of the Oriental, Conrad, Peninsula, Four Seasons, Shangri-La and etc.? Thanks.

All I know is that “Bangkok” And “Phuket” are the most unreal sounding and hilarious names I have heard in years.
Most all of the hotels you mentioned will have promotional specials if you go to their websites, look for links for promotions and special offers, sometimes they offer an extra night free or discounts on certain lengths of stay. You may also want to try: http://www.hoteltravel.com/thailand/bang… or similar hotel websites to compare prices. Good luck.
Usually, direct contact with the hotel concerned may yield promotions that may not be publicised on the net. What you can do is to shortlist the hotels you plan to stay in and check with them on any promotions that they might have. Even if they have none, check with them your booking for the week if they will give you a discount for long stay. July is not peak travel season, so you are likely to find some offers from some one.
Good luck.
Try asiatravel.com as they might have good deals from time to time.
To make sure that any discounts that you receive are bona fide, compare them with the offers here:
Click the “Sort by location , price and star rating” link
Bangkok: http://www.cheaperthanhotels.com.au/Thai…
Phuket: http://www.cheaperthanhotels.com.au/Thai…
It’s my experience that most of the deals undercut travel industry staff discounts and sometimes promo rates etc etc, but have a look anyway.