We have and do swing with other couples, but both prefer MFM, MMFM, etc. She has tried a ff, but would rather have a dick. I too am straight and do the recruiting. She has also gone out on date nights and once I was her and her date's chauffeur.
My wife is definitely more sexually active, and I've lost some steam over the years, but since she is in her late 50s, finding a third has gotten a little more "challenging".
six for sure, 3 plus myself (twice) when I was with her, but we got seperated a few times that day/night, so there could have been more than the one I knew had her alone in our room.