Never fished down there, but know that flounder will take spoons and just about anything presented correctly. Reds will take spoons and shrimp or crab patterns. Trout will do baitfish patterns or spoons likely. I have no idea what a gafttop is.
For $90 I'd make sure what's involved. That's exceedingly cheap. That might only be for a couple of hours, no gear included, etc. Full day charters should run you at least $300, and that's cheap. If I was down there, I'd be expecting to pay $400 for a full day of fishing from a boat inshore. Offshore I'd be looking at $500-$700 for a day.
There's guides and charters that can do it on the cheap, but $90 won't even fill a guy's boat with gas for a day. Unless that's a share price, and you'll be fishing with four or five other guys in one boat. That's doablbe, but a gamble. You may get a boat full of drunken clowns all crammed into a 20' Boston Whaler with one guide to take care of the whole lot. Or you could get another father and son out for a day of fishing and have the time of your life. But for sure make sure what's included-lunch, hours, gear, licenses, cleaning, processing, etc.
For surf, watch the tide. An incoming tide in the afternoon can bring fish up onto the flats as the tide brings cooler water and baitfish. You may go fishing at 4 AM on an outgoing tide, and the flats are flushing, and you're left with 4" of water over marl and matted grass.