[39Xallday]

To state the obvious, doing it yourself with clean wash mits, two bucket method and clean microfibers is really the only "right" answer short of a higher priced detail. The 4 guys are likely going to be using the same sponges they used for the previous 100 cars and will almost certainly swirl your paint. The autogeek detail forum is an awesome resource but beware of the rabbit hole haha. I take my wife's car through the touch less wash every once in a while in the winter but 90% of the time do it myself.

Edit: with all that said if it's your only option the 4 guys gas station wash should be fine, even if they swirl it, it shouldnt be doing any permanent damage, might just need a polish every year or other year.