We live on the extension close to highway 9 (expressway 9? motorway 9?) on Sukhumvit and I like to call it "local" -- i.e. I've only seen a couple of permanent westerners around. I mention the highway as a positive because if you drive it's definitely better to be close to a highway onramp than sit in Sukhumvit road traffic for 10 minutes just to get on the highway.
There are two ladies at Big C near Pu Chao BTS that speak English but it's not hard to get by without any Thai unless you're completely lost. Imperial Samrong is okay but nothing special.
There are at least two apartment buildings being built near Chaeng Erawan BTS and I think one is almost finished at Pu Chao BTS.
Samut Prakan immigration is easy to get to and (in my experience) has short wait times if you come after lunch -- and it definitely beats driving/commuting all the way up to CW (if living on the border of Bangkok province). However, the Samut Prakan immigration office has more requirements for extensions and the like so it would be worth comparing requirements with CW and Samut Prakan immigration first.
There's not much in terms of casual bars that I've found; we usually head up to Onnut or Thong Lor for that. Having said that, there's a beer bar near Chaeng Erawan BTS (or it might be the naval academy station) that seems pretty chill. Western food is a bit lacking unless you're happy with having fast food and pizza a lot. If you live with or have a Thai friend nearby then it'll be a lot easier since you don't speak/read Thai.