I went to one of these combat flight centres in Los Angeles with a colleague. I had 30 minutes in an F16 cockpit with the scenery projected onto the wall in front of me. It was rather like a giant version of FS2004.
I flew at low level down a canyon which was great fun and then shot up some oil rigs. Afterwards, I definitely felt sick for about an hour. Interestingly, my colleague also felt sick and he has 2000 hours in Phantoms.
The next day I had 90 minutes in a Stearman at Chino which included about 15 minutes aerobatics followed by about 20 minutes chasing other Stearmans at low level round a lake with me doing the flying and didn't feel sick at all.