That's funny. I always use a 900MHz baby monitor for my race trailer for those long trips when I'm in a hotel.
But, I have to say I really like my Scorpio SR-i500. It's a little key cahin pager that not only sets your alarm but tells you what sort of mischief is going on with your bike as is happening (or if you are out of range it will tell you exactly what time your bike was disturbed). It has a great range though. It's got some cool addon features too.
Victor
http://www.scorpioalarms.com/