To the OP:
It's not much of a stretch to say Longs Peak is done every summer day by people exactly like you and your dad. I've never understood the allure of Longs when there are much cooler mountains (referring to standard routes; if we're talking technical variety, Longs is unmatched), but if it's caught you in its siren song, there's no harm in going for it. The Keyhole route throws a bit of everything at novice climbers: marathon length, scrambling, exposure, crowds. If you really want to test yourself (and your dad), Longs is a great peak to attempt as a first 14er. Just be aware that doing so would diminish your chances of success.
If you're looking to increase your summit odds, any of the other mountains suggested in this thread would work. Grays/Torreys or Quandary are rewarding first 14ers. Bierstadt is equally easy, but the views aren't as nice. Crowds are an issue on all Front Range peaks.
But since you're coming all the way from Wisconsin, let me propose an easy 14er that's worth the trip on its own, lacks crowds and offers arguably the best 14er summit panorama in the state: Handies Peak. Climb in July and enjoy the wildflowers. If you feel good, Sunshine/Redcloud, Uncompahgre or even Wetterhorn (similar scrambling/exposure to Longs without the heinous approach) are there for the taking in the following days. Visiting Lake City is worthwhile in itself.
To everyone else:
Wait, not everyone drinks beer the night before a 14er? What the hell do you do while you're packing?
“There are two kinds of climbers: those who climb because their heart sings when they’re in the mountains, and all the rest.” - Alex Lowe
"There have been joys too great to describe in words, and there have been griefs upon which I cannot dare to dwell; and with those in mind I say, 'Climb if you will, but remember that courage and strength are nought without prudence, and that a momentary negligence may destroy the happiness of a lifetime. Do nothing in haste, look well to each step, and from the beginning think what may be the end.'" - Edward Whymper