I typically just do logic's mock tape compressor at like 2.0:1 to 2.5:1 with a threshold of -5 to -10. stock release and attack time. If I can hear it working too much, I back down on the threshold.
I really can't imagine going over 3.0:1, it would really sound squashed to me I think. I leave any further squashing to the mastering of the song, but even then I don't exceed 3.5:1, it's like I hear all the mixing efforts getting killed. I guess it's important to note I typically don't mix a real set of drums, but sometimes.
For free and PC, I always liked the Vanilla Compressor. Very transparent.