In terms of recommending, I'd say tell her to get a Wii. It's simple and if she doesn't play games as much, it wasn't that much of a costly investment. Equally, if she wanted to play online, I'd recommend a PS3. If she's not playing regularly, she wouldn't get inconvenienced by having to shell out 60 to play online. Lastly, for cheaper games, I'd say have her get a 360. 360 owners seem to be quicker to return games, so the prices tend to be lower when shopping for used games(in my experience).
You could just show her a couple trailers and see what type of games she gravitates towards and suggest from there also.