Nothing wrong with a Taurus, they were good cars, reliable, and drove decent. No major issues to worry about, just the common stuff you would be concerned with on any car of that age, is the engine solid, is the automatic transmission solid?
If you are going to be using it mostly for a commute, do you really need the extra size of the Taurus? While they are fairly nice cars and are efficient, they are still midsized, and are efficient for that class of car. It will be better than your truck, but not exactly a miser. A Grand Marquis or Crown Vic from the same era is capable of getting nearly the same mileage, and are larger and have V8 engines.
Have you considered an economy car, the Ford Focus was pretty solid, and with a manual transmission and a light right foot were capable of impressive MPG.
Myself, I drive a 1998 Neon Coupe with 5 speed manual transmission, 148K, and it runs like a top hasn't need too much work, and gets an honest 35MPG in town, well over 40MPG on the road.
$18.60 a day driving your Wrangler.
$12.17 a day in a Taurus (assuming 23MPG for the commute)
$6.67 a day in a economy car capable of 42MPG (which is pretty typical for economy cars with an overdrive transmission)
Weekly differences are:
Wrangler $93 a week.
Taurus $60.85 a week
Econobox $33.35 a week.
Yearly
Wrangler $4650
Taurus $3042.5
Econobox $1667.5
Annual savings (I assumed 50 weeks a year of commuting, I imagine you get vacation days where you don't drive to work).
Wrangler $XXXX no savings
Taurus $1607.50
Econobox $2982.50
This is simple math, nothing fancy, I assumed $4 a gallon gas, you stated 70 miles a day commute, I used that figure, and the numbers represent nothing but your commute. If you would use the second car for ANYTHING besides your commute in place of the Jeep, then that would increase the amount of savings, but was outside of the scope of your commute.
$5000 can easily buy an economy car less than ten years old with fairly low miles, liability and Uninsured/underinsured motorist coverage would probably be less than $300 a year, assuming you are over 25 and don't have a lot of wrecks. It would take a few years of driving the mid sized car to make up the money it costs to buy and operate it, although I haven't included maintenance, but I bet total cost of ownership per miles is much cheaper on a Taurus or econobox than a Jeep, so that is a very real savings. Given lower total cost of ownership of an economy car it would only take a year or so to pay for itself, probably two and a half on the larger car.
Another issue here is the lower miles the Jeep will have after a few years, this increases it's value, the Taurus or econobox aren't going to be as strongly affected on the resale value, as they fairly low resale value cars to begin with, the extra mileage hit won't be much, maybe $500-1000 on a ten year old Taurus or Economy car.