Hi,
I've heard a lot of people using the senn. 421 pretty much as a standard for toms (I would like to try on one). I have been using a CAD m179 on the rack toms and an adk hamburg on the floor tom and I'm pretty happy with the results.
An Sm 57 is definitely a mic to have, it is also pretty much a standard mic for mic'ng guitar amps, and snare. I have an audix i5 which i'm really liking a lot. I have been using it on snare and on my guitar cab. I'm mic'ng up a blues jr. and i like the i5 better than the sm57 for it. It sound more open, not as boxy sounding. But, I've only tried the i5 on snare, so I haven't compared it on snare to the sm57.
I also picked up
a nady rsm-2 which is really great on my vocals and acoustic guitar. And I also used it as a room mic when recording drums.
I like combining a closer mic like an sm57 or an audix i5 with a condensor or ribbon mic on a guitar amp and mixing them together. You have to be careful that they don't phase each other out. Once you get into using more than one mic, you have to be careful with phasing. I've been using the the 3 to 1 rule, which which would mean if the mics are 5 inches away from the source, they should be 15 inches away from each other.
Anyway, I hope this helps.
evt