I will be installing a hose spigot in a lower patio area that, till now, has had to have several lengths of hose to provide water for some potted plants. There is an existing spigot on a 3/4" copper pipe on the other side of the house a good 65-80' depending on the route I choose to take. I plan to tee off of it and then it will go one of two routes to the lower patio. 

Digging a trench may not be an option due to rock and trees in the way so, it may be exposed to sun light, which would be a good reason to go copper but that could (will) get costly and be a lot more laborious then PVC. 

If I do go the PVC route should I use the same diameter pipe as the copper service? Do I have to bury it? If I can't bury it, what are my options?