Stay with 3.08s. GM didn't pick those gears for no reason. The one-hour highway driving stretches is the key factor. 3.08s puts your car's sweet spot at the 30-80mph range, IMHO. Engine rpm, exhaust noise, occupant comfort, and gas mileage are all factors. Plus, you'll be spinning the accessories 20% faster on the highway with 3.73s which will lower their lifespan.
That's true, 3.08 shines at 80mph and up but doesn't do so good at 60 and even worse at 50mph, where it's kind of sluggish. The RPMs are just too low at these critical speeds. I spend much more time at 50 than at 80. Given OP is on the East coast, in NC, it's obviously different from a more flat terrain than say Arizona. I would factor that in the equation and go with a lower gear.
I spent a while trying to figure the best compromise, despite my skepticism, I came to realize that 3.42 is the best for sedan and 3.73 is the best for station wagons. These are big, heavy vehicles and they could use all the torque you can get. Especially in hilly terrain and loaded. If in doubt, go with 3.73. You can always put a large tire to change the ratio numerically down.
Now the OP has almost 28" tires which are 3% bigger than stock 27" tires. So if you put 3.42 in, you are not going to get 3.42 but more like 3.32.
I have 3.73 gears in this wagon but I can control the gear ratio with tires. I have a winter and summer tire. If I want more of a highway gear, I can put in a 28" or a 29" tire which will really bring it down numerically into the 3.50 range. Right now I have a 26" tire, which aside from looking stupid on the wagon raises my ratio to at least 3.80. Believe me, that beast needs it.
In most daily driving, the MPG difference is less than you think. Unless you do 100% highway driving on a flat, straight surface at 80+mph. 80% of the time, IME, 3.73 is more useful than 3.08.