For a point and shoot, if you're going to get more zoom remember that lens shake will increase sustantially and the images aren't going to come out so clear. Megapixels don't equal better quality nescessarily... 7 should suffice. Give serious thought to at least an entry level digital SLR and maybe a zoom lens to go with it. I take it you don't need anything press quality, so you might be able to get a decent zoom and body for under $700 and that would completely blow away any point and shoot you own (and the consumer models offer neat automatic modes).

I would say the quality of the sensor and the increase in megapixels makes it so there is less quality loss as you crop in, but a high quality zoom will always be better than cropping in digitally.