Look into the Stable Lodge on Soi 8. Should be LB friendly but not 100% sure. They have a nice pool but nightly rate is greater than 800 baht. If I recall correctly, more in the 1500-1600 baht range. Pretty close to NEP.
The Majestic Suites are LB friendly and are roughly 1500 baht. Very close to NEP. Although they do not have a pool, they will give you access to the pool of their sister property, the Majestic Grande, which is 2 blocks away. You'll have to walk there to use the pool so that is a little bit inconvenient. FYI--Majestic Grande is in the 3000 baht and up range but LB friendly.
Also 2 blocks away from NEP is the Aspen suites. They have a lovely pool. Cost is about 2000 baht and up. LB friendly.
If you are willing to spend about 2200 baht, then Dynasty Grande has a nice pool and LB friendly. Close to NEP.
Also, Nana Hotel is very close and has a pool. LB friendly. However, I don't like to stay there anymore although I have some fond memories of it from the early and mid 1990's. Read reviews of it at Trip Advisor for clarification. I think you can do better.
Google Nana Plaza. You should be able to find a map of it. It is directly across from the Nana Hotel and around the corner from the Majestic Suites. Hope this helps.