If it's for your wife and power isn't as big of an issue then I would go for the 4stroke. It's less maintenance and starting is probably going to be easier too, especially if you do a CRF with electric start.
If you're a honda guy you like the CRF's.
A buddy of mine teaches a beginers dirtbike school and he uses several differant size CRF's and they've been great bikes for beginers and up. I thought the 200 was a good combo between a good learner and something you could still have some fun on after you got better.
