You wife should get the bike that she feels fits her and is comfortable with not the bike you want her to get.
Mine got a Sportster, lasted 18 months, moved to a Heritage. Luckily it was during the 100% MSRP trade on the sportster for the Heritage.
She had put 22K on the sportster.
Her 09 heritage has 90K on it. It is still her favorite bike
She had an 11 Street Glide, and just traded it for her 13 Street Glide. The 11 had 38K on it when she traded it.
She loves her street glides, but like I said she kept the Heritage and likes it best.
Reason she gets the street glides is for cross country trips its more comfortable, and she can carry more stuff.
Since April of 2007 when she got her first bike she has rode just over 150K miles.
She has two bike, the Heritage and the Street Glide.