You can get a single entry tourist visa from Savannakhet. The visa will be valid for 3 months. You will get a 60 day entry and you can extend by 30 days at immigration at Kap Cheong.
You will need your passport and copy of photo page along with 2 photos. You will need one additional photo for the Laos visa on arrival.
Sometimes they will want to see an air ticket out of Thailand around the date your next entry expires.
How many have you had already? If this is your 3rd in a row or more you could have problems.