If your BMW R1200GS is a bit too tall for your comfort, consider a set of high-performance Ohlins lowering shocks. This kit will effectively lower your seat height by about 7/8" while improving the ride quality over stock considerably.
Adding Ohlins shocks is the single greatest chassis improvement you can make to your bike. You will immediately notice an improvement in handling, ride quality, comfort and chassis feedback both on-road and off. Common feedback from riders is that it makes the bike track better off-road and handle better in the curves thanks to damping that is much more progressive than the stock shocks (progressive damping means the shocks compress more on small bumps to give a cushy ride and firm up more on big bumps to improve handling and feedback).
Ohlins shocks (built in Sweden) are specifically sprung and oil-damped for your bike and its intended purpose. They install using exisiting frame mounting points and hardware; there is no drilling or frame modifications required. Since riders are different weights, carry different loads and have different riding styles Touratech does not keep Ohlins shocks "on the shelf" but instead will require information from you when you order about your weight and riding preferences to insure you get a shock that is not too firm or too soft but instead is just right for you and your bike. This "built to spec" service is free and part of the price of the shock. As such delivery from time of order to time of shipping is usually about 10 business days.
NOTE: it will be more difficult to place the GS on its centerstand. Sidestand works OK.