i use a 70m rope for most of my rock-climbing endeavors and know a number of other people who do - although they all live in the slc area. i have mainly used it for cragging and multi-pitch day routes. (i have used it for ice climbing in the past, but i have since acquired 60m half ropes that i prefer to use for that purpose.) you really don't NEED a 70m rope, but sometimes it is a very nice thing to have around (like what jason said above about being able to rap 35m pitches without having to have 2 ropes, as well being able to link pitches of that length when leading multi-pitch routes). when i replace it, it will be with another 70m rope. my partners usually have 60m ropes that we can use if we're doing really short stuff.