My boss owns and flies a '60s Cherokee 180 that I think he bought for around $60k. He's put tens of thousands into upgrades over the years and is now considering a Seneca twin which would most likely be at least $100k. We are in the middle of Texas, do business all over the state and driving to the corners of the state would take at least 6-8 hours. In his plane, it seems flying 1-2 hours is better than driving that much, but trips over 2 hours are not very fun in such a small plane. Not to mention, we get grounded by weather quite often, and sitting on the runway when it's 100* outside, and inside the plane (with no air conditioning) is probably 130*, is pretty stressful.
We've been getting more business in Arkansas and Louisiana which is why he's looking at the Seneca, we'd get there a good bit faster. Mind you, it's not like you just show up to the airport and take off. There's at least an hour or two of planning beforehand. Depending on the aircraft and distance, you may or may not save that much time. It all just depends on what you got and where you're going.
I agree with the previous posters that it won't save you any money, the maintenance and gas alone will kill you. But, if you own a business and can put most or all of the aircraft expenses under the business, you enjoy flying, and it saves you some time on most days, then it can be a worthwhile endeavor. My boss has no debt, lives in a paid off modest house, I'm sure he has over $1 million in savings, makes probably $150-175k/yr between him and his wife, and spends his extra money on toys like his aircraft, motorcycle and travel trailer. If flying is your thing (and we all have one, don't lie), then it could be fine.