dave your getting me all excited with all this talk of isaan and laos......
i cant comment on udon,as i only passed through there,all i can say as they got a nice food market near the station.........i have heard there is some hot nightlife too....good clubs full of uni chicks,im guessing same sort of vibe as KK city.
i stayed KK city for 3 days,so not a great deal of experience...... what i could make of it was thats its very laidback for a city.............i enjoyed myself thouroghly,visted a few nightclubs,which were heaving with lovely white skin city chicks,visted some nice venues,thai show,band ,music....very thai..i couldnt make out a word the comedian said,555555

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me and my pal didnt have no probs hookin up with some local chicks.but wasnt on the p4p scene,not sure of the deal with the pole dancers in the clubs,all i know was they were feckin smokin and had quite a few friends,heard there is a Go go in KK,no doubt its worth a look.
now, vientianne........
again quiet laidback city(i suppose i compare a lot to BKk),thats sort of comes alive at night and i would say the weekends,but not saying weekday is a bad time to go,no way......
some nice places by the river and waterfall to chill and have a beer lao,but different vibe compared to LOS,defintely a lot more undercover on the girl scene,more of a hook up on the sly witha FL type get together.
on the hotel front,i run into some problems,like girls getting kicked out early doors because manager was due in,but then just done a bit of research and found some more friendly hotel shall i say,ive covered this a bit more in my round the world thread,probably some other helpful info there to on the later pages........
a place that i would love to go back to(and i dont know the name),was this hotel,it was massive,near a main road but sort of plonked in the middle of nowhere at the same time,great club on the roof,banging tunes,all added to the amazing surroundings,believe this club was only open weekends,some nice totty in there too

maybe someone can shed some light on the .name
any other questions ,i'll be more than happy to try and help ya out.