I put white faux-wood 2" horizontal blinds up (Walmart sells a decently priced one by Better Homes and Gardens). I keep a bucket full of the extra slats from when I shorten them to fit, just in case someone breaks one or a dog chews on one. It's been about five years and I've never had to replace or fix one, though.
For small bathroom windows or kitchen windows I put a cheap tension rod up with some curtains that match the room. If they have their own they're welcome to put those up. Every tenant I've had so far just uses what I have.
@Peter Z. They haven't been too bad as far as dust (I have them in my own house, too). I can run a vacuum attachment over them and it cleans dust right off...if they really get gross you can pop the whole blind out of the holders and hose it off outside, lol.