I'll go out on a limb and pronounce KL as my favourite shopping destination in Asia. The reason is there are several huge shopping malls all within a dim sum throw of each other. They also tend to specialise in items like gadgets, sports gear, shoes, jewellery, luggage, high-end European labels, high street Western brands ... I could go on. You could easily spend a day in each, especially when you add a cheeky massage or fish foot spa to your day.
Dubai
From the high street American and European brands at the enormous Mall of Dubai to the gold market and spice souks, there is something for everyone here. And here's a bonus: drop the kids (and husband) off at the ski field in the mall where they can tackle everything from junior rides to black runs and you can try on clothes in Top Shop without being nagged.
Santa Monica
My favourite stopover city is Los Angeles for a number of reasons (beaches, sunsets, restaurants and rooftop bars), but the shopping stretched along Santa Monica's three pedestrianised blocks has pretty much everything you look for in America. Santa Monica Place is home to Bloomingdales, Nordstrom and a top floor of restaurants, bars and a food hall, so I could bob along here all day.
Bangkok
My tip to travellers heading to Phuket or other beach resorts is to add Bangkok on at the end and save your shopping for there. What you'll find at the beach markets is very "same same" but in the city there are several malls (MBK is attached to Pathumwan Hotel and its 2000 stores are open until 10pm) and markets. Chatuchak is the biggest in the world with 9000 stalls in a warren of makeshift alleys. You'll need to drop breadcrumbs. Here's my blog on the best way to navigate it.