Formule 1, Ibis, Sofitel...we've mentioned all brands of the well-known company apart from the most useful one:

Mercure. Decent deals to be had as long as you book online! That's where I stay if I've got no time/will for research...
Last year I went to one in Lyon...Got a top-floor room on the corner with incredible views all over the city for €65! Granted it was during a weekend (IIRC Sun to Mon), the rate didn't include breakfast (even better because I ended up munching croissants in a tiny local café) and they wouldn't give me any miles (they only do at more expensive rates, at least for OK+ members), but still was fantastic value.
A word of warning, some of the hotels are not in the city centre because they're primarily designed for people travelling by car so are closer to the motorways etc...but they're always denoted "suburb" on the website so you've only got yourself to blame if you mess up!