For shoppping best area is PRATUNAM .You may get a lot budget hotels in this area. Once I stayed at Pratunam Pavillion Hotel for 07 days and cost me around 4000 Rs per day for a double room with breakfast.
You find travel agents there (Tuk tuk drivers knows all the stuff but some can't speak english). I have got 02 packages for my family from them to see safari world and siyam theme park with tickets, Lunch and transportation for 19000 BHT.
In addition , You could visit River Kwai and Tiger Temple where you get tamed tigers living with monks. But entrance fee is comparativly expensive (600 BHT per head).Also Madom thusad branch is there and found around 50 nos wax figures
As far as garments are concerned, I think you can buy same quality garment in Sri lanka for a little higher price.Branded ones are really expensive and those could be found in here for more or less for the same price.