First, thank you so much for everyone who has responded. I've learned a lot from this thread. Ignoring the things that appear to be a wash, that we don't have evidence of, or that aren't as important to me, it seems like I can distill the differences down to:
1.5 Advantages
Much cheaper (leaving money for the 3.0 upgrade)
Physical shifter (I strongly prefer this option)
2.0 / 2.5 Advantages
New Bumper (2.5 only) (which I love) (potentially nullified by the 3.0 upgrade)
Double DIN dash (2.5 only) (I wonder how a single DIN aftermarket unit with a pop out display would look on the 1.5s)
Quieter ride (potentially nullified by some aftermarket work on the 1.5)
Wider selection of tires
Center info screen
Power gauge on instrument cluster
Premium seats
Lower interest rate on loan
More Comprehensive list:
1.5 Advantages
Much cheaper (leaving money for the 3.0 upgrade)
Physical shifter (I strongly prefer this option)
Higher quality contractors?
2.0 / 2.5 Advantages
New Bumper (2.5 only) (potentially nullified by the 3.0 upgrade)
Double DIN dash (2.5 only)
Quieter ride (potentially nullified by some aftermarket work on the 1.5)
Wider selection of tires
Improved HVAC
Center info screen
Power gauge on instrument cluster
Premium seats
Glove box
Lower interest rate on loan
Hopefully that list will also help others that stumble across this thread in the future who are having the same analysis-paralysis that I am. After making it I was surprised how many advantages I actually had down for the 2.x, but I was also surprised at how minor they were compared to the price difference.