Lookup the Sunflower near Silom. Quiet, cheep, convenient close to BTS. Nice people with breakfast, street food and good coffee nearby (also entertainment if you are interested). About a motel 8 level. Since I found it. I usually stay there on the way to Phuket (15 years of travel). I have a condo in Phuket and have explored BKK a lot over the years. I usually avoid the 4 and 5 star hotels. Because I am often just passing through and not a general tourist. Use Agoda to book the place. There are lots of others near by. The Royal Garden is also nice with a rooftop pool and bigger rooms farther out on the BTS.