4 toms, a kick drum, a hi hat, three cymbals all at once is enough for me. Failed miserably at piano as a child, only drums had a calling.
In the city i live in, it is inundated with drummers and hardly any decent guitarists, as a result there are some really good drummers out here that either sing or play guitar so they can gig. Many instances in bands where drummers have stepped up to the front line, or vise versa from playing guitar.
I have a switched on friend who teaches kids guitar, and the first thing he teaches his students is some drumming basics. This helps them learn where things fit in. It also helps them to develop time keeping and rhythm.
Even though i don't play another instrument i do understand some bass line and piano basics and a bit of theory about singing and other musical knowledge. It doesn't pay to be totally ignorant, it is these other instrument that you have to play with and understand where your part fits into it all and some other than drum musical knowledge is certainly beneficial. You can also confidently argue musical points with your band mates when something isn't quite right.
