fuzz -
I have a friend who rides the same way as you do. Just cruises the mountain, stays away from the terrain park. He's an intermediate to advanced boarder and he just picked up a Ride Decade in the ATV collection (which is an upper end freeride board for the company). Ride boards are stiff, and with exception to the Mobility collection are suited primarily for freeride cruisers.
Uisce made a good point about the wood core, but wood cores are unfortunately heavier than the lighter fiber boards. Also I've heard good things about Arbor boards as from the name you can tell are made of wood. Have another friend who rode a K2 for awhile. Maybe he thought a ski company would make a good cruising board. It was descent but he got a new Libtech board which he swears by. Might wanna look into those, no personal experience here though.
In terms of Burton and Forum, they are mostly terrain boards and offer some freeride boards, but I'd take a Ride Decade over a Burton T6 anyday. Plus the Burton is almost twice the price. Forum boards (which is what I ride) are also very stiff and very fast, but really suck at cutting into icy slopes. I'm actually thinking about getting a Ride ATV myself for that reason.
In terms of boots, if you've got a history of bad ankles, or want to keep a clean history of bad ankles, I'd say boots are very important. Right now I've got a pair of DC Emblem with BOA laces. They're super stiff on the ankles which gives them super protection, but my toes get really cold on cold mountains. BUT the good thing is they have pouches in the soles to insert foot warmer pads (havent tried using heat pads yet). The other thing, the main reason I bought these boots is the BOA lacing. No more having to tug on the shoe laces with all your might. All you do is twist a knob and the laces tighten themselves.
Bindings - I'm really not sure about what's out. I have Forum ATP bindings which are pretty stiff and nice. But they're discontinued and I don't know what replaced them. Ride makes descent bindings, as do Drakes but Drakes are also in the $250+ range. What not to buy are the clickon boots and bindings, or FLOW bindings. Burton bindings aren't that great. I actually sprained my ankle a few years back with burton bindings on because they didn't provide enough protection.
Regarding board size, it's not really a matter of height. It bugs me when people gauge board size on height. You could be 5'5" but if you're a tub of lard and weigh 220 lbs, you'll probably need a 165cm board rather than a 153cm.
If you're 5'9" and around 200lbs you'llprobably wanna go with a 159-163. If you're cracking 230, then you may wanna ask someone who sells boards (by that I mean not some schmuck at sports challet but maybe the dude at a rental place). Remember the longer the board, the faster it'll be and the harder it'll be to control.
Anyhoo hope that helps.
btw I have a pair of size 10 Burton Moto (lower end of burton boots) that I don't use anymore. If you want 'em they're yours for the price of shipping...though it goes against Uisce's advice of spending the bigbucks on boots