I'll weigh in here and of course I don't near the dives some of these others have. First thing I'd recommend now that you have your NAUI OW cert is to do the Advanced course. This is the route I took (completed May 2015) and it really opened my eyes to how diving should be. Yeah, the initial OW course made me want to dive and taught me how to do it, but the AOW course really got me excited about it! Allowed to me to check out some of the advanced skills like night diving, search & recovery, deep diving, etc. It wasn't until after I got my AOW that I started purchasing gear.
Now this is probably highly unorthodox, but my first real gear purchase (needed a wetsuit - 5mm, 2 lights, tank marker, and compass for the AOW so I had those) was a Hog D3 1st Stage, Mares Viper Octo, and an Ocean Reef G-Diver full face mask. I'm pretty certain a full face isn't something you typically see new divers jumping into (pun intended) but I knew it would drastically increase my enjoyment of diving due to not having to worry about mask fogging, leaks, etc. And to me, it's just a helluva lot more comfortable. They're not for everyone. They do take getting used to and they are a bit cumbersome at first. But now that I've got a few dives under my belt with it, mostly lake dives, there's no way I'm ever going back without a really good reason. Expensive piece of gear for sure, but for me, it's been worth every penny!
Next round of gear purchasing was my Oceanic ProPlus 3. For no other reason than I didn't like diving tables. Tables account for the square dive profile, which you NEVER use. Depth constantly fluctuates adn tables don't account for that. Having a good DC simply gives you more bottom time. And they make diving not quite such a daunting task. Set your alarms, periodically check your gauges, and enjoy the dive! When the alarm beeps...time's up. Just my viewpoint here. Not to be taken as low for sure.
Round 3 was my BC, which was a Father's Day gift from my wife and children. Zeagle Brigade. I dove several rental jacket style BC's and just didn't like how they made me roll side to side in the water. Tried a rental back inflate and underwater it was night and day different. Seems at this point you and the Mrs. have already purchased most of your equipment, but I at least would've recommended trying each type of BC to see which one worked best for you. Maybe you did that. Not all BC's are crated equal for sure. I picked one that worked well for me and have thoroughly enjoyed diving it!
Last piece of gear, which I purchased this past weekend and am waiting for it to come in....tank. Only reason I even picked one up is because I could've bought one by now for what I've spent on rentals. Now, if I want to drive a couple hours and go dive (going with my wife to do her OW dives this weekend), I can load up my gear and go. If I'm going on vacation somewhere....the tank is staying at home.
Looks like you're int eh market now for a reg set. Do some research. Read reviews. See what people are using and what works for them. I was recommended the Hog D3 by my LDS and so far it's been a great reg. Not a budget killer ($290 First stage, and I think $180 second stage) and I really like the swivel feature. First dive on it was in 54 degree water and it worked perfect. Doubt I'll ever get much colder than that honestly, so I don't need something that's good for ice diving. Just find out what works, try out different ones if you can, then decide from there.
Bottom line....the best gear to buy is the gear that makes you want to dive often! Whatever gear gives you the most enjoyment out of diving....you really can't go wrong!