How should i go to these places in Bangkok within one day?

I agree with the earlier post that it might not be possible to do all that in one day. Sampeng open early, I went there before (don't remember what time) but it was early I think around 8am and it was already open. If you're a shopping-holic you will likely spend half day there without you noticing the time (it's a very large place). This is one of the reasons why one day might not be enough to go to all places you listed. I don't know much about other places but if you use google map you might get a good idea of which order to go to save time and taxi fares.

It's near impossible to shop at those five places in half a day simply for a few reasons: (1) Bangkok traffic around those five market areas are more heavily congested than other areas; (2) it will be Christmas Saturday morning and Saturdays are normally the busy shopping day as well as for the traffic in general; and (3) I don't think you come all the way to these markets to buy just a few small items. I think it will take you at least 6 hours to cover those places. Get up very early and finish your complimentary hotel breakfast by 6.30 a.m. or latest by 7.00 p.m. or skip your breakfast at the hotel altogether. You can grab a bite to eat at Sampeng. First, take a taxi to Sampeng by leaving your hotel no later than 7.00 a.m. If the shops in Sampeng are not open yet you can get something to eat there. Second, Balanna Market is adjoining to Sampeng and within walking distance. Third, take a taxi to Wang Lang Market which is located at Tha Pra Chan Pier adjacent to the Grand Palace and no more than 10 km. (likely less than 8) north of Balanna Market. Fourth, go to Khao San Road by taxi which is only about 3 km. from there. Last, go to Bobae Market by taxi which is about 4 km. East of Khao San. Good Luck

I would take a tuk-tuk it's fast - can be cheap if you negotiate properly .... Can't answer for the other places but Khao San Road doesn't open before 9:00 - ie there will be some shops open - but most will be opening if you show yourself at 9:00 - Takes a good hour to go up the street so arriving at 9:00 is fine, because it gives you the time to go up the street and look into the early open shops and get back down the street to see the late opening ones.

Ok. after investigate your targets I think you could not complete it in one day. However, below guidance may enjoy you; Bobae, Sampeng are wholesale market but Bobae focus on Cloth market, while Sampeng focus on gift, shirts, stuffs market. If you need clothes, go to Bobae market not Sampeng. You may spend around 3-4 hours. After shopping, go back to Indra regent and leave you stuffs there, wash yourself and sleep. Then go to Khaosan road in the Christmas Party in the evening!

Why make a problem for yourself choose one place and spend the time there One market is pretty much the same as another if its for clothes as they all sell the same things And you are near Pratunam so you dont need to go that far anyway Khao San road is better in the evening in the day its pretty much empty Do your market things in the day and go Khao San about 830pm for a dinner or something