Juat an additional few things I can add, as MM has covered the most important things (Communicate and leaving her to experiment alone are really good ideas):
Firstly I assume your wife has been used to manual stimulation for a reasonably long time? This is her first vibrating toy, the sensations are completely different from using fingers or a tongue and it can take a little while for a lady to start enjoying that new sensation. Imagine completely changing the way you masturbate, imagine going from using your hands to now using a vibrator on your penis..... you can see how it might feel strange on unusual at first until she relaxes into the idea and experiements some more.
Another thing, the vibrator may be the same size and shape as you, but its different entirely as well. It isnt attached to you, it vibrates etc etc. I think if you asked us ladies who use vibrators a lot we would say this: Sex with your partner and using a vibrator both feel good, most of us prefer the sex not only for the nice feelings but to bond with our partner, to make love, to feel him getting excited etc etc. The vibrator is different, it is used to make us orgasm, they feel intense but in a totally different way. Also quite a few of us ladies use vibrators on our clits, rather than using it in the same way as simulating sexual intercourse. So another suggestion would be asking your wife to do both at the same time! Best of both worlds :D Use the vibrator to tease her clit while you are making love to her. Maybe she would enjoy that a bit more? Not to mention, she might feel a little bit "on show" if, at the moment, you are using this toy on her, as she lays back and thinks of england. Knowing that you are watching her. Does that make sense?
Try using the toy on yourself. :D No really! I think it will be nice for her if she is a bit daunted by the whole situation if you hand it over to her and ask her to use it on you, try rubbing it over your perineum, balls, over your penis and if you are really brave...anally. I think she will relax into the idea of toys more if you play around, make it fun and are prepared to give it a shot yourself.
Make it fun, crack a few wise cracks, lighten the mood...(bursting into the room in your underwear, with a blanket cape, weilding the vibrator like a light saber whilst making the humming noise might be a bit too much but would make me laugh lol :P)
Dont play with it for too long at first. Instead of using it as the main course, intended to give her orgasms, use it as a tease, tell her you are just using it as a tease. When you sense she is struggling, switch to her usual form of stimulation. You will probably find eventually, if she isnt under pressure to cum from the toy, that she will cum from the toy. (Us womenz are a pain in zee ass right! :P)
Try different toys, but I would wait a little while. If a truck load of vibes turn up she might start panicking, but it might just be that the toy you have at the moment just isnt right for her, and another one will work. We all have different preferences when it comes to toys. I mean I dont really like bullets, and I dont really enjoy rubber toys (friction and irritation) but other women love a good bullet. Its probably something that isnt considered when buying toys at first but all vibrators feel different. From light buzzy teasing mosquito high pitched toys, right down to deep rumbly rolling vibrations and everything in between. Then you have pin point stimulation toys like bullets and rabbits that target a small area, and you have more diffuse vibraters like wands or larger toys that just vibrate over the whole area. You will only discover what your lady likes by trying different toys over time.
Hope some of this helps.
