Hi Berty,
I am 5'11" with "short legs",and an old bugger in his 50's. I found the Dakar ok around town, once I loaded her up, she is a bit of a handful to get her off the side stand, a litle bit of muscle so to speak, on the road no problems.
You can always get the seat modified in Thailand very cheaply.
If I had a choice I would go the Dakar over the standard.
However if you are just going to hoon around the MHS loop etc. go the GS., it's suspension is much tighter in the curves with little suspension dipping as with the Dakar.
The price depends on the K'S travelled, my Dakar has done 50,000k, a 2002 model. I can only get $5000Aust as a trade.
They are a good all round bike,reliable and cheap to maintain. I will use mine for another big trip tomorrow, if I had the money.
"I used to spend all of my money on fast cars, women and booze, now I just squander it." George Best 1946-2005 RIP