As another has stated, get a 1200. After that, unless she's into bar hopping or short runs around town (which gets old real soon), get the Sportster with the biggest standard gas tank available and forward controls...or just get her a Softail or Dyna and be done with it!

 

If she is relatively new to riding I would say to get a newer 1200 custom with the fat wheels. My friend is new to riding and he took it for a test ride and loved it. I have also seen threads on this board from those who test rode one and they also said it was the most well balanced sportster they had ever ridden. Just my .02 hope this helps

 

Take her to the dealer and let her decide. You can make adjustments on any of the available sportsters for her comfort, but she's gotta love looking at it. As far as others' advice.. I disagree. 883 is plenty of power for me. I want to do upgrade it with a 1250 kit someday, but I don't feel like the 883 is underpowered at all. As many people prefer mid controls as forward controls, so only she'll know that too. Getting the biggest gas tank available isn't necessarily good advice either.. I think the 4.5 gallon tanks make the sportster look like a totally different bike than the 3.3 or 2.2 tanks. Sure it'd be nice to go further than 100 miles between gas stops, but I've gotta be able to stomach looking at it too. My 883 with the peanut tank is not a bar hopper.. it's seen over 1000 miles this month, and gets a lot more action in the warm season.

 

I agree with getting a 1200 motor. You might not want to go with a 1200 Custom with her because it comes standard with forward controls. It sounds like she is a relatively new rider and may feel less in control with her feet in front of her rather than under her, even at 5'10."

As always, the best suggestion is test ride or rent for a weekend to try them out.