Here are the four I have. Your right, you cannot go wrong with any Beemer bike. You will get a lot of opinions but get the one you think you want depending on what type of riding you want to do and how much & how far. Time will tell if it was right. If not, get another type. R, RS, GS, /2, /5, /6, /7 whatever... You can't go wrong if you use it for what it was intended for.
One tip may be to stay away from the 74's as the trannies had a weak link and most folks were replacing them with the 75 trannies.
Couple links for ya...
http://vintagebmw.org/v7/forum?p=5413&highlight=&sid=9c14a1dcb857987beb373081e36f53e6
http://www.advrider.com/forums/index.php
http://marketplace.ibmwr.org/
http://www.bmwmoa.org/
http://motorcycle.jaxed.com/cgi-bin/mash.cgi?cat=mcy&fil=&itm=bmw&state=&ps=&pe=&ys=&ye=&so=d&submit=+GO+
And of course get with your Dealer.