It's hard to pick a winner, but this one's near the top of the list. About two, maybe two and a half years into the hot wife thing, we had an encounter with a guy recruited from Craig's List. The screening, vetting, and seduction all went very smoothly. KK found the guy quite physically attractive, as well as mentally/emotionally/intellectually stimulating.
The screening date went really well - I watched KK fondle, then suck the guy's thick cock in the back seat of our SUV. She was too greedy and excited to wait. The guy finger-banged, then tongue-fucked KK to orgasm. Having "passed the interview," we gave him the invite for a full encounter that night at our hotel.
Before parting that afternoon, the guy asked if he could bring some toys to play with during the encounter. KK told him, "I love toys... the more the merrier."
Later that evening, the guy showed up at our hotel suite at the appointed time. He had a small backpack in hand. As we got started, there was a point where KK was splayed out on the hotel bed, completely nude save for her fuck-me red pumps. Our guest had tossed the backpack on the floor alongside the bed. He'd already joined KK, kneeling over her, so she could suck and fondle his thick, throbbing cock. At a point, while slowly fucking my wife's mouth, he leaned over, grabbed, and opened the backpack.
I was in sort of a state of shock at what came out - two realistic canine dildos, complete with knots. Things seemed to be happening almost too fast. The guy started fucking KK with the dildos, eventually positioning my crazed wife on her hands and knees, fucking her ass and pussy with the realistic phalluses. There was a moment where he went ass-to-mouth on KK, feeding her the veiny toy, watching her fellate it like it was a lollipop.
The guy was pretty skilled with the dildos, and very kinky, dirty-talking KK the whole way. He pleasured my wife for about an hour with the two dicks, until she was shaking and shivering from so many orgasms. The guy finished in the kinkiest way possible, getting a double-barrel blowjob from KK, his cock, and one of the dildos simultaneously - he blew an enormous load all over KK's face and lips. Her slutty finale was cleaning both cocks, slurping and licking up all the cum from the dildo, and his cock.
The whole thing was mind-blowing; ultra kinky, perverted, dirty, nasty. KK really, really got into it.
After that encounter, KK hooked up with the guy on her own, on the sly, at least twice that I know of - she was sort of obsessed with his toy collection, his thick cock, and dirty mind.