I would probably try and refrain from upgrading if possible.

A new groupset isn't going to make a difference. My bike's got SRAM Rival, and I've switched bikes with my friend. There bike has a Sora/Tiagra 8 speed mix and it works perfectly fine. Just make sure it's tuned up.

Also, new wheels probably won't make a difference either. I'd just stick with the wheels you've got unless they break.

If I were in your shoes and had to choose, I'd go with some Soul 4.0s. They look pretty sweet.