You are lucky that you are tall enough to learn on a dual purpose bike. Get one and you will find that not only are they entertaining on multiple surfaces, they also have the best layout for controlling the motorcycle in street riding situations. VWW
By your description, I would say that a used Suzuki DRZ-400S, Honda XR-650L, Kawasaki KLR-650, or if you are really cash strapped an old Yamaha XT-350 would all be excellent starter bikes for you, as long as you don't do much freeway commuting (they all have very short gearing so they would rev an buzz too much for long freeway stints)
If you want a cruiser and only a cruiser, try the Honda Shadow 750 or 1100, or the Yamaha V-Star 650 or 1100, Suzuki Intruder 800, Harley Sportster 883 or any other 600 - 1100cc "cruiser" none of them are waht you would call "fast" and they tend to be quite reliable. If you really like this class, stay tuned, because we'll be doing a "Middleweight Cruiser" comparo in about 30 days.
if you are looking for a cheap but nice powered sportstouring bike, try the 1200 or 600 (both with the same frame; whereas i'd never choose the 600). even for beginners, the power and torque are easy to control and the bike is.. err.. what we call here "sweet-tempered"
i know everyone is praising its own bike, but i had some bikes before and i fit best on the current..
Let me second the KLR-650. It's cheap, even cheaper used, bullet-proof and the aftermarket has all sorts of goodies for it. You will be amazed at the leg room on that thing. With the stock 16 tooth counter shaft sprocket on it you've got freeway gearing to spare. I switched to a 14 and still found it ok at freeway speeds and it liked the dirt a whole lot more. I've done quite a few 500 mile plus days on it in comfort. Plus, I've taken it through some gawd-awful passes in Colorado and lived to tell the tale. Just let the shop adjust your valves.
I've owned or extensively ridden the other DP bikes Sean recommends too. He is spot on.
About the review, just one thought: could you include a vulcan 750? There is not one review in the whole MO archive and it is the last specimen of a kind of bike very few people are still attracted to.
I hardily recomend the DP bikes. I also am tall and found them quite fun, and fit my lanky frame well.
As a plus you can do some reasonable dirt riding on them. Buy used and enjoy, if after afew months you are tired of your buds raging on you about not having a proper bike (XRFLSTGSXR1yz600 etc) then you can start saving for that bike, and you will know what style of ride you like better. Don't sell the DP. I did and regreted it.
As others have said before, you buy motorcycles, never sell (you can always find some place to keep them).
I'm 6'4" and all leg, so I feel your pain, especially when cramped up on my buddies SV650S. My first bike was a bandit 600. Very comfy for me, inexpensive, mostly reliable with extensive aftermarket and owners group backup. DO NOT GET THE 1200!!! 1200 owners joke about never needing to replace the front tire, because it is never on the ground. 1200's will power wheelie pretty much at will. Sound like a beginners bike to you?
I still have my bandit. With significant time and a bit of money I turned it into a not too embarassing track bike.
Are you sure about the cruiser style. I find the extra low seat height on cruisers to be a hindrance, with my long legs. Every time I stop, I don't feel like the strength of my leg is supporting me; or if I need to muscle the bike around I wind up standing half the time, to make it easier to control the bike.
Not all cruisers, but most feel like the seat heights in the sub 28" or lower area.
I agree with Nplateau. A bike like the Suzuki V-strom DL 650 is an excellent choice. A similar option would be the Ducati Multistrada 620. The roomiest most practical coice is going to be a standard style motorcycle with a taller longer travel suspension. Most of the bikes in this category are biased toward street riding like the V-Strom or Multistrada.
At your height the cruiser and sport bike styles are probably best avoided. I am 6'0" and find most sport bikes to be pretty cramped for extended journeys.
I am a little under 6'3" and have really long arms and legs. But I have actually had very little trouble riding even really tiny bikes (I loved the Honda 599 MO tested last spring) and I spend a lot of time on both a FZR400 and a CBR954RR - both bikes most would consider cramped. I think that what actually happens is that you adapt yourself to whatever you ride.
Having said that I think that a particluarly excellent bike for you would be a Honda XR650L. I happen to own a 600R and it is an amazing machine that is way comfy for long pounding rides.
The V-Strom 650 is a cool bike that would suit you ergonimically but might be a bit much to start on and similarly a TDM850 is one of the greatest bikes in the world for tall people if you can get your hands on one.
I'd agree with this, except it sounds like this guy is a little strapped for cash and there are few used DL650 out there. He'd be better off with the KLR as recommended above for two reasons. First way cheaper than a DL. Second, about 80 pounds lighter. Between his height and his bicycle experience, he'd feel right at home on the KLR.