I agree with Bev & Jerry - Go for a Sound Head that will accept eight or more inputs - you never know when you'll need to add an extra "hired" musician to give you a Bluegrass, or Celtic, or Old Timey, or Country, or Whatever sound. It can make you way more versatile. Trying to find room for them in too small a set-up can be a real pain.

There was a good thread a few weeks ago on microphones (anyone got the blue clicky stick handy?) that should give some insight as to types of mics.

It's a real toss-up between a mic or a pick-up for instruments. Our group (four piece) is coping with a lead singer who plays rhythm guitar and has a hard time hearing herself in the monitors. When we take her guitar mic up to the point she feels comfortable, the guitar is so "boomy" it drives the rest of us crazy. We're trying to talk her into trying a pick-up that can be equalized a little better.

What is a real pleasure, but usually not affordable, is to bring along your own sound technician. They can do much of the humping of heavy gear, check out how all of you sound at the same time, get your drinks, and drive back from those gigs that are 300 miles from home! Sleeping with one (but not more than one) of the band members is an optional perk!