I'm looking for a very good restaurant with Isaan food specifically, doesn't necessarily be Isaan orientated otherwise. Sukhumvit area would be the most convenient, but can go for further for this one as well.

I've heard some good reports about Isan House, down and off of Sukhumvit soi 4. I think they might have traditional dance shows as well if it's a special occasion and not just for lunch. Also Cafe de Laos over on Silom is a very nice looking place (with a website). Vientiane Kitchen and Hualamphong Food Station used to be popular places on Sukhumvit (soi 36 I think) but they've possibly closed or moved.

As far as cheap, authentic, rundown Isaan places go I'm sure there's a pretty long list, and everyone has their personal favourite.

Enjoy your somtam, laab, gai yaang, sticky rice etc.

Thanks. Will check them out next week.