You're in Bangkok. You want to go out and take in the city but don't want to deal with traffic. What are your options? Well, you have many.
I find walking easiest for short distances if not raining (rainy season from July to October). You can walk around but you won't be able to cover much ground. The main reason people don't walk much is the heat and humidity (hot season from March to June). You could get on the road by taking a:
Tuk-tuk (haggling required)
Locals on short journeys to and from work are the primary clientele, but they're not adverse to tourists using their services.
You can go practically anywhere in the greater Bangkok metropolitan region by bus. It takes time to familiarize with the lines of buses in Bangkok and it is not always easy to get information in English.
But all of the above will have you stuck in the notorious Bangkok traffic. Bangkok traffic jams among world's worst. Drivers can spend an average of 64 hours a year stuck in traffic.
The best option to get around Bangkok inner city is to take the Skytrain (BTS), which is my favorite. You don't have to worry about traffic. It's a cheap, smooth, clean, fast way to get around Bangkok. One day pass is the way to go. It will save you a LOT of time in rush-hour. If you have the option, AVOID rush hours (7-9 am and 5-7 pm). It’s hell.
You can also use MRT subway. It's designed more for the residential/commuter passenger.
I later found out that there is no photography on the Skytrain (oops). How do you like to get around in Bangkok? Let me know in the comments.