A nursery should be a space that you enjoy being in too. It should also be youthful enough for a baby. This means that you may need to venture out into a somewhat of an unusual theme. Really bringing in the rustic design style is going to accomplish this brilliantly.
One thing that you want to consider doing is going with a unique wall mural. In fact, you can even consider bringing in the landscape from outside right into your own home. You can just take a lot of motifs that would otherwise seem a little bit cheesy in the rest of your home and use them in these spaces. You could even hire an artist to paint a sunset. You really just need to think about what the Southwest kind of vibe means to you. It might really mimic a wide open space or dramatic mountain views. This is also going to be one of the few themes that is gender neutral because it will work for a boy or girl. It can still add in a lot of blues and pinks in the mural that is going to be a lot more subtle than just your basic baby pink kind of shade.
You also really want to consider the tone of furniture that you choose to go with to match wallpaper borders or fitted wardrobes. In this case it makes a lot of sense just to go with wood tones. You could make it more sophisticated with the darker cherry wood, although you need to stick with a simple mission style so it won’t seem too elegant. You can also go with taupe paint finishes. Really white furniture is going to be too stark and modern for this kind of space.
Since this is an unusual theme for a nursery you may find that typical pieces like mobiles or lighting fixtures are really difficult to find. In this case, you may just need to shop in the adult lighting section for a lot of iron pieces. You can also bring in a cowboy theme with a mobile with lots of a boots or different farm animals on it.