My 2 psi -
Start with rec wreck. Air or nitrox single tank. Get good at that then move up to doubles/mixes/deco. Here's why; this is different than caves, different than deep. There are lots of popular wrecks with varying degrees of difficulty, warm water and cold, fully intact and fully disintegrated. Start at the less challenging end and work your way up the 'degree of difficulty' chain. As to recommendations - for beginner to intermediate rec wreck I like Conch Republic Divers. Gary and his gang know their s**f and have access to everything from The City of Washington to the Spiegel Grove to Duane and Bibb and more. When you decide that this is your gig there are hundreds of wrecks everywhere a boat can float, (and sink). Warm, cold, salt, fresh, lakes and ripping current. And they won't laugh when you show up with your dry suit. Well, they laugh at me and my dry suit, but that's different.......
DC
DC