I stayed at the new Ibis Styles Sukhumvit 4. It just opened a few months ago. It has a roof top pool and bar. nice rooms. The buffet breakfast is excellent. Huge choice of food. A complimentary shuttle is offered to Nana BTS station. You can walk there in about 10 minutes. This one is so nice, I am going back there for 12 days next year.
I also stayed at the Ibis Styles Bangkok Sukhumvit Phra Khanong Hotel which is now about one year old. I found this to be very nice also. The buffet breakfast is very nice, there is an outdoor sitting area if you prefer to eat out there, also a bar and pool. Rooms are very nice. A short walk to the BTS Skytrain Station. This one tends to be slightly less expensive than the one above.
I can recommend either one of these to you. You can't go wrong at either hotel. Hopes this helps you.