Using fantasy and dirty talk is a great way to incorporate experiences into your sex life that may be either logistically impractical or simply outside of your comfort zone.
It sounds like you’re already on the right track with the blindfold. It’s amazing how much having vision taken away can heighten an experience — it’s also a great way to increase the feeling of vulnerability. When your wife is blindfolded she’s counting on other cues to let her know what’s going on, and what you say and do will be the biggest cues of all.
Try adding some fantasy talk or dirty talk to the mix. You can simply spin a story for her, saying outright that there are other people present, addressing comments to these other people about her, saying things like, “Isn’t she gorgeous? What would you like to do to her?” and so on. You can use whatever language fits in with your dynamic and the experience you’re trying to create.
If talking isn’t your thing - or if you’d like something to heighten the experience after the dirty talk - you can also try noise canceling headphones. If you take both vision and hearing away, she’ll have a hard time knowing what’s going on in the room around her.
Whatever combination of restraint and sensory deprivation you decide to use, you can also play with the element of surprise in the way you touch her. You can change up your usual techniques, touching either more roughly or more gently, mimicking the way someone else might touch her. You can touch one part of the body, stop, and then start somewhere else altogether, as if there are people standing around her taking turns. You can also use sensory toys to really change things up - everything from feathers and fur to things that poke or scratch. You can even use ice cubes or glass or metal toys that can be warmed up or cooled down.
Changing from sensation to sensation is a great way to keep someone just slightly off balance, and if that’s done after the suggestion has been made that multiple people are participating, it might be easier than you think to slide into that fantasy.
As with all sex and kink play, make sure you negotiate ahead of time. People have limits that can extend into the fantasy realm as well. Some people may not want to participate in group play but think it’s hot as dirty talk. For others, even the mention of other people involved may be upsetting.
However you decide to play, fantasy exploration is a great way to try new things and to break out of routines - have fun with it!