I'm ALSO from KC. I've played in lots of bands-currently in The Gaslights and a soul covers band called Shakejoint. Formerly of Pendergast.
I use a 22 watt Deluxe reverb for guitar. Anyone who thinks you NEED to have a 100 watt guitar amp is smoking crack. In fact, it's best you DON'T, if you don't want to overpower the p.a. in most clubs you will EVER play in. That is, if you're tone conscious and realize that your 100 Watt Marshall sounds terrible on '1'.
To play with a drummer and hear everything, something in the 20-40 watt range is more than adequate for guitar. In bigger places, it'll be miked anyway, so you don't need the extra power. I should qualify that-I'm assuming you're talking about a TUBE amp, yes? Because solid state amps are generally a lot less loud than their equal tube powered counterparts. (and generally sound like crap.)
If you absolutely, positively MUST pin an audience to the back wall, do it with a 50 Watt Marshall. At least the soundman will have a fighting chance of getting the vocals heard.
Bass is different; you usually want it to remain pretty clean, and bass frequencies eat up a lot of power. So you need more overhead. Generally, 300 watts will be enough to get the volume up where you need it with clean headroom to spare.
My advice: Go to some shows. See what others are using. Get similar gear to the guys whose tone you like best. It's a good starting point.
Chris