Because your new, you dont even need to be buying a splined setup.
Go on Ebay, or check your LBS, and get two 24" Torker Lx unicycles. These are cheap unicycles, and you can probably get them for below $100.
Both 20" and 24" unicycles are a good size to learn on. Starting with a 20" will make learning tricks easier, like the basics of freestyle, trials, street, and flatland. The 24" can still be used to learn the basics, but because its bigger by a few inches, it make learning some of the stuff a little bit more difficult, and take more effort than doing it on a 20" wheel, though the 24" will allow you to ride faster than the 20".
For right now, start with the basic Torker, learn to ride, and start experimenting. You said traveling will be a good reason to ride, so after you get proficient with the small, basic uni, you may decide you want a bigger uni, with more speed, and then you can buy a 29" or a 36".
You may also end up getting interested in Muni, trials, or street, and end up needing a uni that can take the abuse, you can start looking out for the splined unicycles. I recommend to use 24" for muni, and keep with the 19" wheels if you ever decide to really get into trials, street, or flatland.
Of course, this will all come later when you are more experienced and can pinpoint what styles you want and like to do, and you may end up with having multiple unis, one for each style. PM me if you need any help with anything. Ill be glad to help.
EDIT: About your inseam, just buy the uni with the longest seatpost, then you can cut down to your height. Dont cut too much off or you cant raise it if you ever want to, and dont cut too little off or else you cant lower it without cutting it again, so find a good size that allows for a good seat height, and a few inches of down and up adjustability.