KLM lounge at IAH is great - self-serve bar, light food (usually soup, sandwiches, snacks), free wifi, newspapers. It is only open from 1-4pm, though - so that's the big downside. There were issues a few years ago getting in as a Skyclub member/DM, but you can get in now if you are on a SkyTeam same day flight. It is located in Terminal D, so you have to take the train from A to D, but at least it's post-security.
The AF lounge is smaller and further at the end of Terminal D and they will not let you in if you aren't on the AF flight.