Is it under dialogue? If it is maybe you can find a word or words from another take to edit in surgically. If it isn't under dialogue, cut in some ambient room tone. NR works best for hiss and hum removal or reduction - a constant frequency.
I would not use compression since compressing is for reducing volume on peaks.
When using compression, to bring up the average signal level, you have to turn up your overall volume for that channel, thus bringing up the low level noise - and in your case, creaky floor.
I would try the crackle and pop filter mode in the Sony Noise Reduction 2 plug-in, you can download a fully functional demo from sony, it just adds an annoying beep periodically but you can tell exactly what it will do and won't do using the demo. I needed it to remove some fan noise and it worked like a charm. It's kind of expensive ($280) but you can get it bundled for free with Sound forge 8 which comes with CD architect (for only $250 $50 rebate) from BandH. Mark