Admittedly, I've never transitted through AMS
myself - but from the experience of family members, I'd say avoid it at all cost.
- admitted, there are a lot of hotels around it, but I always found the airport itself (inside the terminals) to be a bit boring, as in "not much to do"... barely any shops to browse through, not much in terms of restaurants... but then again, I've only seen 2D
and 2E or 2F (not the one that collapsed, but the one that TAM departs from).
As for FRA
- I admit that I might be somewhat biased there, but I've never had any problems here at the airport - and I use it several times every month. Admittedly, I don't connect here, since I live in Frankfurt it's either my origin or my destination. But even before I lived here, I never had trouble occupying myself in the terminals - and there's dozens of hotels around the airport, plus the Sheraton directly attached to the terminal... and downtown is only about 15 minutes by train, and there's dozens more hotels there (and, of course, restaurants, bars, shops, ...).
Personally, I'd use FRA