This is my second stay at Citadines Sukhumvit 16 and I returned after trying out various other hotels for my frequent visits to Bangkok. Amongst the other serviced apartments in NaNa and Asok area, I recommend this one hands down.
The location is fantastic - very near to BTS Asok and a mere 3-min walk. We are not inconvenienced by any tuktuk schedules and do not need to make long distance calls to the hotel to despatch one to pick us up. You do need to know where to walk though. If you are taking the BTS, look for the exit which says "Exchange Tower". Take that exit and you will see Exchange Tower with a huge True Fitness sign. Get down from the sky walk, and walk along the road on the pedestrian walkway. Exchange Tower will be on your left, the road on your right as you walk against the flow of traffic. Turn left on the first slip road you see, and you should be able to see Citadines - it is an orange building with a purple signboard.
Walk further down along this slip road and you will find Foodland... A 24-hr supermarket. I bought eggs and ham and instant noodles to cook at the apartment. If you are not a good cook, next to the hotel is a quaint coffee house that sells pretty good chocolate croissant and banana cheesecake. (Don't ask me how I know! LOL obviously I caved in and bought them for tea).
The toilet is comfortable, and everything works in the room. The only minor grouse I have is that the bed is uncomfortable. It feels very hard and there does not seem to be much support. I can sort of feel the springs... And the pillows were so thick, I made my own out of towels and my T-shirts.
Otherwise, the hotel staff is very helpful and always tries their best to give me directions to where I want to go. Would recommend this as an economical option for accommodation.