I am really liking the Coffee House and City Street soundsets. I’m going to be running a game of The Strange in a few months, and those will be really useful for the modern Earth segments of the game. Far different to be meeting in a Starbucks than, say, a disco club or friendly tavern.
If you guys end up doing other modern soundsets, I could recommend an Office soundset. Lots of games have you infiltrating offices (either before or after hours), or taking meetings while you try to sound out who’s hiring you today. Office phones ringing, office chatter, computers typing, copier/printer/fax noises, coffee pot brewing, water cooler bubbling, key card beeps, the HVAC kicking on (that is an amazingly loud noise that you don’t realize until it’s gone). For “behind the scenes” action, maybe a computer server room (for hacking purposes, naturally), or a security guard making his rounds (“Are you authorized to be on this floor?”).
Also a Police/Emergency Room soundset! Lots of player characters get into trouble with the law, or try to avoid it, or end up needing to get patched back together . Having sirens, police scanner chatter, officer comments (“Let me see your ID.” “Freeze!”), handcuffs rattling, etc. Or gurneys rattling, medical machine beeps, medical jargon (“Get his/her vitals.” “BP is dropping!”), curtains rattling open/closed around emergency room beds, doctors being paged over the hospital intercom, and so forth.