Pamestique 

All good recommendation but frankly... it is just best to have your wife visit with you to your local bike shops and just ride bikes... especially if she is a newbie. Don't push her to ride something she is uncomfortable on... and as to saddles, depends on the bike. If she wants a hybrid/sports style bike the saddle will be wider.If she prefers a real road or mountain bike, the saddle will be and should be narrower. A wider saddle can actually be very uncomfortable. But sometime it takes riding awhile to realize that.

Obed7's advice is right on... While I don't particular like Trek, the company, they make a full line of bikes that appeal to women riders... for instance the Domane WSD bikes are something to check out.... I have three friends that I helped get into cycling and each like the Domane... for the money, bike (depending on level/price point) comes with good components)... when you purchase a bike, I suggest adding in a different saddle as part of your negotiation... alot of women like the Terry Butterfly. I won't ride anything else...