Pattaya - Vientiane ( Laos) Thai Embassy , same day
You can leave Pattaya and get you visa application in on the same day ..I've just done it .. you still have to stay overnight in Vientiane to collect you passport & visa the following day
Fly from U-Tapao 07:20
Arrive Udon Thani ( UTP) 08:30
Bus UTP - Nong Khai Border 08:50 - 09:50
taxi quicker
Cleared Thai exit & Laos entry Cutoms by 10:30
Taxi to Thai Embassy arrived at Embassy 11:10 ( No queues )
I was number 513 at embassy - Passport was ready at 3:15 , so I didn't go an d queue like everyone else at 13:30 - I went at 15:00 - no queues