For small gigs 25 - 100 people I am using a Peavey Escort 75 watts per channel, very compact easy to "roll" to a gig and back to the car. For larger venues (I play 200 - 275 people tops) I use my Yamaha 300 watt (150 per channel) with 10" speakers. Now as Mike stated a lot depends on the venue not actually the amount of bodies there and just as important the type of music she will be playing. If it is a small pub with dancers and listeners and no head bangers she will do fine with nothing larger than I use. If the opposite is true she will need more power as per Mike's photos above.

Now if I were starting over I'd get the Bose PA (highly recommended by many in the know on this forum) as for the venues and laid back crowd I play this baby would be powerful enough for the smaller end of my audience to the larger end.

Good Luck,