Quick to set up and portable - 102ED f/7 and a 180mm f/15 Mak.
http://web.me.com/nicholas.loveday/Site/Misc.html
Of the two I use the refractor more, often leaving the Mak behind. Speaking of things that stay collimated, when assembled the scopes do stay parallel within about 10 arc minutes, and even the 50mm finder is usually pretty close to aligned when fitted.