I hear many folks love http://www.bilstein.com/
shocks are great Shock upgrade. They are firm (but not solid) and last a long time.
Also.... Please remember that shocks reduce "ease of" up/down movement. Air Bags, Timbrens, extra leaf Spring, etc. create more support. Some folks confuse needing new shocks (due to sag) from needed better support (due to sag). If your vehicle has sag with 5er connected, it needs rear suspension upgrade. If your vehicle bounces more then 3 consecutive time (ya, the famous bounce test), then it needs new shocks.
If you are connecting a large / heavy weight 5er and get immediate rear sag, do investigate Timbrens SES units. re: http://www.timbren.com/ses-kits.htm
If wondering, my buddy across the street has a large 5er with Timbrens SES units on his Pickup, and he loves them. re: Install it / leave it and NO air leaks or "air up / air down" changes to worry about. And, Timbren SES units can be installed by many DIY folks.
Hope this helps...