My only other abdominal surgery was a c-section, and that was definitely worse than WLS. But, I'm not going to lie, that first night was a bitch. I was lucky, I did not have the gas pain.
I had a Lap GB on February 7, and today I have been off pain meds four about 3-4 days, and I was only using them at night for about 5 days before that. I even cleaned, walked to get my daughter from her bus stop a few blocks away, and managed steps, etc.. For a long time, the only pain I had was standing/sitting. Once I was in position, I was comfortable.
I do suggest, if don't have one, borrow or rent a reclining chair. I slept sitting up for several nights after surgery. Once I was sleeping in bed, I used pillows under my torso to help with discomfort.