You are talking about some pretty expensive upgrades.. You can get the Overland wheels on Amazon for about a grand (not including tires). As far as the headlights, yes - LED headlights do require a custom harness, and that gets pricy as well. If you wanted the headlights like some of the higher trim models, well that gets super pricy.
I have a '14 Laredo too, and I'm a huge fan of how it looks over the Limited. For one, it has the painted mirrors and door handles. I never liked the look of the chrome handles or mirrors. Now the SRT is on a different playing field, so don't compare the Laredo to that.
A good place to start is the front bumper chrome insert. Costs less than $30 from the dealer (may have to order it), and takes a little bit of time to put it on, but it looks really good. It is what the Limited's have on their front bumpers. Makes a difference for sure.
'14 Laredo DIY: Front-lower-bumper-chrome insert
Tell your girlfriend to enjoy what she has. She spent way too much on a truck to not love everything about it. But, I do applaud you on wanting to helping her change some of the things she does want to change about it..