So let me start off by saying that I have been to Soldier Field 5 times for concerts (and many other times for Sporting Events) and I have never sat in Section 234 or 204. I am going to be in Section 204 for Chicago 2 in June and I'm really excited about the seats. But getting back to your question, here is what I know, and have experienced with Soldier Field and how they will relate to these sections, and I will let you decide what is best for you. Section 204 is in the Club level on the East side of the stadium. It will be to side of the stage, and my hope is it will provide a great view but you may not see the screen well. These seats are face value $70, and the next section over (section 205) is at the top price point of $280, so it tells me that the view may be a little limited but probably not enough to worry about. Row 6 is not covered, which is actually a good thing, which I will get back to in a second. Section 234 is on the west side of the stadium and closer to the '50' yard line. The face value on these seat are $280 and will provide a good view of the stage. The only issue with these seats is they are covered by the 300 level entirely. So Row 4 will be under the next deck. This is a good thing in case of rain, but I have heard that the sound echos in this level, which for a football game not a problem but for a concert where you want sound to be the best, its no so good. So it is completely up to you, if the cost is about the same, I would probably roll the dice and go with 234, but if 204 is cheaper (which it should be since the face value is so low), I would save the money for a T-Shirt and sit in 204. Here are some helpful links that you can refer to in help you decide.
3D viewer of Soldier Field: https://soldierfield.net/general_seating
Section 234: http://aviewfrommyseat.com/venue/Soldier+Field/234/
Section 204: http://aviewfrommyseat.com/venue/Soldier+Field/204/