From what we've done in previous years you can use limit switches to do a lot in a very simple way, so when you have boolean aplications, like an arm that only has two positions switches can do the job very well. This year we've used them to set a zero point on our elevator, this way every time it went back down the zero on our encoder would reset to avoid problems with it getting lost. Our team really likes to use this kind of limit switch
http://www.amazon.com/ME-8108-Adjust...s=limit+switch they are very robust, adjustable and cheap, so we can keep it simple and still do a lot with them.