I owned two 1GEN tundras (04 DC & 06 AC) before my current 2006 Tacoma DC
What I noticed:
~ The defrosting capabilities were much better in the Tundra. I live in snowy, rainy, foggy New England. Lots of moisture. Not having heated mirrors & a defroster that works well at times is a pita. Say what you want about heated mirrors, but if you haven't lived in cold icy climate at times I feel its a hazard. You have to have the heat cranked to make the windows clear & stay cleared. I run it at the 2nd to the last setting not full defrost. That seems to work best.
~ The MPGs in the Tundra & Tacoma are the same. I get the same mileage in my 4.0L V6 that I did in both my 4.7s V8. Both were 4WD & auto. One tundra was a 4spd. The other was the newer 5. I tracked it pretty closely. Even the larger DC (the 1GEN) got 20 mpg highway once broken in.
~ The bed depth, size,tie downs & bed material will be different. The tacoma composite bed only has tie downs in the back & no locking tailgate. You have to add fixed D-rings to the front of the bed to get good anchor points up front. The rail track has adjustable clamps which are good, but if you need a solid mounting point up front, its a mod you have to do. Also you can add a pop-nl-ock & the hose clamp for added tailgate security. The composite bed is nice & has held up to a lot of use. No need for a liner or line-x but I added a bed mat to stop stuff from sliding around.
~ The rear suspension - I had the Rear TSB done for I bottomed out very easily. The TSB did stiffen the ride a little bit but now the truck does not bottom out when towing, getting mulch, carrying teenagers in the backseat. It still applies to the 2011s for toyota still puts the 3 leaf pak on the trucks in the US.
~ The radio (since you mentioned it). Overall the stock radios used in the tacoma are not that great. Read about them here. Its a easy mod to swap out the deck. I did not have the JBL
& a $100 new deck was a huge improvement. Spend a little more & you have your navi.
~ The Tacoma's interior room is not as wide. Everything is within easy reach, but I felt my Tundras, though a tad dated, was more refined. The shifter is on the floor vs the column. Also the 4WD switch is a dial, no lever. Andthere is no glove box lock fwiw. The Tacoma's interior felt more blingy at first, all the silver accents. I have gotten use to it.
~ The Sport model Tacoma comes with a hood scoop. I would suggest your wife drive a sport. I found it to hinder my view while driving since I am a small person. The Sport models are probably the nicest model though. I bought a nicely equipped SR5 DC w/ tow then modded to my liking.
~ Changing the oil on the 4.0L Tacoma is much easier than the Tundra. The filter is right up front. 20 mins tops & nice DIY thread on here.
~ Parking is easier in my Tacoma. The Tundra AC was ok. The Tundra crew cab was a beast to park lol.
Overall, I think your wife will like the tacoma. It fits me very well & is very similar to my older toyota trucks (87-95). At times I do miss the tundra, the 4.7V8 was smooth as silk. The 4.0L is a little noisy in comparison. I love my tacoma but at times been thinking about the new 4.6V8 Tundra.