You are going to say 24-70 2.8L event lens, but I sold this one already twice as events are only very sporadically and not my cup of tea, as it's mainstream stuff
In the past I also had the Sigma 35 Art, I sold this for the 50 1.4 Art (best price/quality 50mm, better bokeh for halfbody modelshoot).
Later I bought the Sigma 85 Art and doubted to resell my 50 1.4 Art to have the 35 1.4A again (would be better now, seen that I don't have the 24-70 anymore).
But strange enough there isn't much interest, despite that the 50 Art is a top lens for the price.
Back to the topic now, seen my set, would you use a 16-35 f4L IS with flash or 50 1.4 Art for an afterwork party or both ?
The location will be a party room of a company, not sure how big it will be.
There are many photographers who both keep the 50 Art & 85 Art, but this is only 1-2 steps back with the 85 and I do only outdoor portraits.
Last time I had the chance to exchange my 50 with a 35 but I didn't hear anything more. I think i re-check to sell or exchange it again and use more the 85 1.4A.