St Louis Arches?
St. Louis already has a USL team, St Louis FC. I assumed this is the same club to play in MLS, no?
Saint Louis FC (USL) is a separate club but its owner is part of the MLS bid. It is unclear whether they will continue to run Saint Louis FC as an affiliate or directly owned reserve team, or just shutter it. They have already announced they will not use it's name and branding.
I think this was mentioned above, but the lead owner mentioned the "St. Louis Archers" as an early favorite among fans she talked to, but I speculate it's very early in the process and it's much less than a coin flip it wins out.
Some message boards were suggesting "Olympique St. Louis." I think there's IP issues with the IOC, but I think it's a neat name. We haven't seen names inspired by Ligue 1 yet.